B75 w/Turbocharged Thermodyne

[Humbird]

Hi all,

A guy near me is selling a “1950s Mack B75 with a Factory Turbocharged Thermodyne.” He claims it’s one of three. The cab is *quite* rough, but the price doesn’t seem too bad, if it’s actually that rare. I’m just a little skeptical, since I didn’t think those old Thermodynes were really set up for turbos. How can one tell if it’s actually a factory setup? 
I was going to set up a day here soon to go look at it, since it’s being stored a few hours from where I live, so anything to keep an eye out for, telltale serial numbers, or good bargaining chips would be much appreciated. While I don’t typically collect old Macks, I just can’t turn down the opportunity to bring something uncommon to the next truck show! 🙂 

Thank you all!

Here’s the link to the listing.

[steve s.]

If it is the original engine, the model would be a B753, the three denoting that it was turbocharged. The model and serial number should be on a tag on the lower part of the passengers door. The serial number will also appear on the frame near the rear spring hanger for the passenger side of the front axle. The serial would probably begin with B753S, the S indicating a tandem rear axle, if it was built that way. There were a total of 1825 B753 models built from 1955 to 1966, in a variety of configurations. To say that there were only three like the one your looking at might be true in some obscure way, but it sounds like a stretch to me. Looks like a nice truck, and it is certainly worth fixing.

[Humbird]

29 minutes ago, steve s. said:

If it is the original engine, the model would be a B753, the three denoting that it was turbocharged. The model and serial number should be on a tag on the lower part of the passengers door. The serial number will also appear on the frame near the rear spring hanger for the passenger side of the front axle. The serial would probably begin with B753S, the S indicating a tandem rear axle, if it was built that way. There were a total of 1825 B753 models built from 1955 to 1966, in a variety of configurations. To say that there were only three like the one your looking at might be true in some obscure way, but it sounds like a stretch to me. Looks like a nice truck, and it is certainly worth fixing.

This is great information; thank you so much! I’ll look into it a bit further and see if the owner can give me the exact model name. For over 1800 having been built, “one of three” does seem kind of weird. Maybe he’s got details…

[JoeH]

"one of three" claims could mean a couple things....

One of three that he has for sale?

One of three like that that the original purchaser bought?

[Vladislav]

Something looks wrong about the relationship of the engine fan and the radiator shround on the 2nd photo. And that reflects the position of the plate between front bumper and radiator assembly on the 1st pic.

Overall the truck looks nice and these big radiator B's are relatively rare. But it would need some notable amount of work to be brang back on a road for going to a show.

[Mark T]

Almost looks like it has a (74) on the hood.   Vlad's correct, something isn't right with the fan.  Wild guess, but I wonder if it was born with a Hall Scott ?   Then it might actually be one of 3.

[70mackMB]

4 hours ago, Vladislav said:

Something looks wrong about the relationship of the engine fan and the radiator shround on the 2nd photo.

l thought the motor was on the ground at first. Top radiator support rods are cut off and resting on the motor.    .....Hippy  

[terry]

Something really funky on that fan shroud, could it been that high for a Cummins engine?   Terry

[mechohaulic]

On 1/10/2024 at 6:31 PM, JoeH said:

"one of three" claims could mean a couple things....

One of three that he has for sale?

One of three like that that the original purchaser bought?

one of three painted yellow?? the list is endless. 

main factor ;;truck condition vs price 

dollar value vs practicality . 

if you only search for rare go to a steak house.

it's more toward keeping history alive at a price and interest you have

[JoeH]

+1 on that radiator shroud looking goofy. That fan is way low and tiny compared to that massive radiator.

Also, I'm entirely unfamiliar with B's, are the X braces above the engine normal in B's? They've been cut, which is no big deal to replace.

[mechohaulic]

cross braces are not unusual for B's  ; without a doubt there is a lineup situation with fan vs shroud ;; could be one of many items. main point  to consider is :: are enough truck/ parts vs dollar in question worth asking price,??  after purchase/shipping/  rebuild  how far in debt would buyer be ??   major restoration looking at rotten floor panels . obvious not all parts original . broken mounts ? flex hose used for radiator inlet/ outlet. all in all the 75 is one fine looking truck. days at waterbury Mack Trucks myself and another mechanic /wrecker driver  did our darnest to convince owner to replace the old '57 diamond-T wrecker chassis with a trade in Mack B-75 .;; NO way would he. ended up with a B-61 with 10 uni-shift. was still nicer then the ole '57 T. 

[mowerman]

Lots of good looking sheet metal, but it doesn’t appear to be running to me all great comments I don’t have an opinion on price, but as they say yes, there is way more than 3  they really don’t have any antique value if that’s what you’re looking for. Thanks for the post. Good luck…. Bob

[terry]

The outside metal looks good, did you click on the links pics? The floors are gone big time!  Terry

[mowerman]

I didn’t even notice the link I just opened it up. Yes I see what you mean. I don’t know why the cab and  doors are so rough and nose looks immaculate. I wouldn’t even bother with it other than part it out 

[Humbird]

I had noticed the doors and floor panels, but a buddy of mine has a donor cab that’s not in bad shape. The difference in fan and shroud height is what really raised some red flags for me. So I figured I’d ask here. And I’m glad I did, all the info is much appreciated - I definitely think I’ll pass on this one. Besides, I’ve got enough projects as it is! 😅

Thanks again, y’all!

[mowerman]

Yeah I did notice that myself … too many negatives your making the right choice but the B73 and 75 are little more harder to come across… bob

[mowerman]

6 hours ago, Humbird said:

I had noticed the doors and floor panels, but a buddy of mine has a donor cab that’s not in bad shape. The difference in fan and shroud height is what really raised some red flags for me. So I figured I’d ask here. And I’m glad I did, all the info is much appreciated - I definitely think I’ll pass on this one. Besides, I’ve got enough projects as it is! 😅

Thanks again, y’all!

Yeah, same here. I’ve got too much to do. I can’t really take on another antique size. My wife is constantly preaching. You’re not bringing home any more junk… bob

[mechohaulic]

how is it a valuable piece of history to Most females is to be considered junk BUT all the trinkets around the house and chotkeys are thought to be needed?? please pay attention to statement MOST females ==NOT  ALL . imin trouble with one female right now   ;;; don't want a riot in this yard 

[mowerman]

She spends hundreds on hair and nails but doesn’t get anything I do

[mowerman]

Oooooooohhhhh also scentsy we must have about 30 of them around the house although I do like them and they smell real good so I guess they don’t really count

[mrsmackpaul]

Looks to me like the radiator isnt original 

Its orange the trucks yellow, this would explain the fan situation 

As to the price, if it was out here you would get knocked down in the rush to buy it

I would consider it to be good buying at that price 

 

Paul

[JoeH]

Looks like a single frame, and while the cab floor is rotted out it could be a great foundation for a restoration. "Brakes don't work" it's got rotochambers. Swap those out for some 30/30's.

I'd consider paying 2500 for that if I wanted a B to restore. 

But seller would need to explain that "1 of 3" BS.

[JoeH]

Namely, the frame being a single frame and not having rust jacking is a big selling point in my eyes. A cab can be found I expect.

[mrsmackpaul]

2 hours ago, JoeH said:

But seller would need to explain that "1 of 3" BS.

Does it even make a difference 

To me it isn't bad buying at that money

It's a good start for a project and everything after that doesn't amount to a hill of beans as the saying goes

It really is a good start at a good price

All the picking apart of a listing is kinda childish to me as no one is gunna keep it original anyway

I hope who ever buys it enjoys it for what it is 

Would there be many good B model cabs left in the states

They didn't so much rust apart in Australia, more broke apart with metal fatigue with our fantastic roads

 

Paul

[Mark T]

This is an interesting truck. I don't ever remember seeing a floor raised in the cab like that either. 

[mowerman]

If any one knows does it even run or at least not frozen 2500 would be pretty fare just a nose I expect be worth that .. bob