R Model Cabs/differences

[BUDD5670]

I looked at a "1973" R685 and 20 ft dump trailer today I saw in a kinda local classified ad. Sadly there was no title/registration on the Mack, but the owner said it was a 1973. What year did Mack start using the cab with the 3" pushed out back?? My 79 has this, and more plastic in the interior too. The Mack I looked at today had the steel dash and smaller cab, wouldnt that make it 1972 and older?? Also, it had aluminum planetary top casings and round axle tubes, mine has cast iron housings and square tubes. Were these both 38000 rears or were the aluminum toppers lighter??

[other dog]

I looked at a "1973" R685 and 20 ft dump trailer today I saw in a kinda local classified ad. Sadly there was no title/registration on the Mack, but the owner said it was a 1973. What year did Mack start using the cab with the 3" pushed out back?? My 79 has this, and more plastic in the interior too. The Mack I looked at today had the steel dash and smaller cab, wouldnt that make it 1972 and older?? Also, it had aluminum planetary top casings and round axle tubes, mine has cast iron housings and square tubes. Were these both 38000 rears or were the aluminum toppers lighter??

man, I miss those brain cells I abused now...used to know this. The '77 F-model I drove had the bigger sleeper and I used to remember when they changed from the flat rear on the cab...but I can't right now...probably same year on R-models. The instant Rob gets back from the buffet at the Petro he'll answer this, as he is an R-model expert. As in "air's nuttin' 'bout a r-moderl I don't know".

[convoyduel]

man, I miss those brain cells I abused now...used to know this. The '77 F-model I drove had the bigger sleeper and I used to remember when they changed from the flat rear on the cab...but I can't right now...probably same year on R-models. The instant Rob gets back from the buffet at the Petro he'll answer this, as he is an R-model expert. As in "air's nuttin' 'bout a r-moderl I don't know".

The changeover occurred in the '73 model year run, I believe in late '72. I have never found anyone who can pin down exactly when. I have seen titled '73's with both the new and old cab from the factory.

[Rob]

The changeover occurred in the '73 model year run, I believe in late '72. I have never found anyone who can pin down exactly when. I have seen titled '73's with both the new and old cab from the factory.

Yessirr, that is correct. The manufacturer was allowed to deplete existing stocks in production before completing the changeover to the then new cab layout.

Rob

[vision386]

Yessirr, that is correct. The manufacturer was allowed to deplete existing stocks in production before completing the changeover to the then new cab layout.

Rob

That was my understanding as well,but i'm sure mack was like other truck makers,using existing stock first,so it is entirely possible that an older cab made it onto a later chassis. My dad had a friend that bought a new LTL-9000 ford in 1987,he took it back to the dealer with a complaint that there was some rust in the rocker panels under the door sills, he was told the cab could have been manufactured as early as 1970!.....the "L" series cab was just as common on a ford,as the "R" series on a mack...............Mark

[Rob]

That was my understanding as well,but i'm sure mack was like other truck makers,using existing stock first,so it is entirely possible that an older cab made it onto a later chassis. My dad had a friend that bought a new LTL-9000 ford in 1987,he took it back to the dealer with a complaint that there was some rust in the rocker panels under the door sills, he was told the cab could have been manufactured as early as 1970!.....the "L" series cab was just as common on a ford,as the "R" series on a mack...............Mark

There is also another option as "existing stocks" referred only to new trucks being built at the time. This had nothing to do with "service replacement parts" that were in the system. I'm quite certain that if someone wanted the older style cab when specing a new chassis and the changeover to the new cab had already commenced, this area would have been tapped. Remember this was still in the days where Mack wanted to please, and comply with the end user's request/requirements.

Not really this way any longer as we know. The larger cab was welcomed in those days however.

Rob

[bullhusk]

Remember,guys,

Brockway used the old style Mack cab starting in late 74 on the new 700 series, then they offered the 3+ cab as an option only the exterior was the same the interior was ther own. they used the Mack cab up too the 760 with the tilt nose witch Mack stole an used as there Superliner after they shut down one of the greatest trucks ever built BULLHUSK

PS they also had the 760TL,V12-71 475HP & the 1693TA-425 CAT> Motor

[bullhusk]

I almost forgot,

Crane Carrier used the R cab also I think from 69 to 71 for there tractors with the H-beam frames

[Underdog]

Now that you all have this figured out, I will insert the proverbial monkey wrench. At the ATCA Northeast PA chapter meet in Harford Sunday, we came across a 1979 U-model tractor with the plastic dashboard but the SHORT CAB. My friends and I had this same debate over when the cabs were updated, and if the U-model was an exception to the rule, perhaps in keeping the BBC short as was the purpose of the U-model.

[bullhusk]

Underdog,

I have never seem a U with the 3+ cab ! but yet the DM600's built in the 70's & 80' do have the newer cab ! Go Figure??

[Underdog]

Underdog,

I have never seem a U with the 3+ cab ! but yet the DM600's built in the 70's & 80' do have the newer cab ! Go Figure??

That's why I figure the U-model retained the short cab. Same reason for the B-67 concave cab. Shorter BBC.

[BUDD5670]

Now that you all have this figured out, I will insert the proverbial monkey wrench. At the ATCA Northeast PA chapter meet in Harford Sunday, we came across a 1979 U-model tractor with the plastic dashboard but the SHORT CAB. My friends and I had this same debate over when the cabs were updated, and if the U-model was an exception to the rule, perhaps in keeping the BBC short as was the purpose of the U-model.

Are you talking about the green 1979 U model with the airfoil?? My Mack R was there, it was the white and red 1979 crammed between the two yellow bombers, my freinds trucks. Did you see the 1980 DM600 shortened up to a "U" model. I had to do a double take on that one.

[Underdog]

Are you talking about the green 1979 U model with the airfoil?? My Mack R was there, it was the white and red 1979 crammed between the two yellow bombers, my freinds trucks. Did you see the 1980 DM600 shortened up to a "U" model. I had to do a double take on that one.

That single axle DM belongs to a buddy of mine, he got that truck as is from FLA. Whoever did the conversion did a good job. We think engine and trans have been changed- it has an overdrive 2-stick. Originally built as a tandem roll-off chassis.

I had my F-model there, red single axle. It was a good show with perfect weather.

[Underdog]

Here we are at Macungie 2010...