Farmall1212 Posted November 28, 2019 Share Posted November 28, 2019 Just got a B67 and it does not have the center section in the rear. Axles are there. Any idea where I can find a tag or stamping to determine what I need? Did they all have the same rear just different ratios? I am going to use this as a site truck in the mountains so I don’t need it to be brand new. It does have Mack stamped in the rear cover which is welded on and is not removable is that helps in identifying. Can I swap it out with a newer style that drops in From the top? This one comes in from the front. Thanks Quote Link to comment https://www.bigmacktrucks.com/topic/59993-b67-rear-end-model-identification/ Share on other sites More sharing options...
Rob Posted November 29, 2019 Share Posted November 29, 2019 Could be either a single, or double reduction differential originally. Do yo have the driveshaft available with the truck? If so and you'll relay the distance from the center of the rear universal joint to the rear end housing face, one can figure out what was originally there. Most likely a dual reduction unit as several were. There may be stampings on the right axle tube viewed from the rear also that would identify it. Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment https://www.bigmacktrucks.com/topic/59993-b67-rear-end-model-identification/#findComment-436862 Share on other sites More sharing options...
Farmall1212 Posted November 29, 2019 Author Share Posted November 29, 2019 Sweet! I do have the driveshaft but it will take me a few days to get it measured. I will post once I get the dimension. Thanks Quote Link to comment https://www.bigmacktrucks.com/topic/59993-b67-rear-end-model-identification/#findComment-436875 Share on other sites More sharing options...
Farmall1212 Posted December 21, 2019 Author Share Posted December 21, 2019 Finally got that measurement. It is 23” from face of the rear to center of the driveshaft. With it being that much space I would think it would be double reduction but would appreciate any help identifying. Thanks Quote Link to comment https://www.bigmacktrucks.com/topic/59993-b67-rear-end-model-identification/#findComment-438489 Share on other sites More sharing options...
Rob Posted December 21, 2019 Share Posted December 21, 2019 Yes, I agree with a double reduction unit. I'll measure a single reduction unit I have but I'm thinking it's closer to 18", or 19". Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment https://www.bigmacktrucks.com/topic/59993-b67-rear-end-model-identification/#findComment-438494 Share on other sites More sharing options...
Maddog13407 Posted December 21, 2019 Share Posted December 21, 2019 look on the rear pass of rear housing, the flat part to the right of Mack stamped on the tube. should say 507 508 512 . the bolt pattern is all the same single or double reduction. even some newer Mack rears that were off brand housings were the same bolt pattern. deciding factor is will your axle splines slip into the rear Quote Link to comment https://www.bigmacktrucks.com/topic/59993-b67-rear-end-model-identification/#findComment-438497 Share on other sites More sharing options...
Rob Posted December 21, 2019 Share Posted December 21, 2019 7 minutes ago, Maddog13407 said: look on the rear pass of rear housing, the flat part to the right of Mack stamped on the tube. should say 507 508 512 . the bolt pattern is all the same single or double reduction. even some newer Mack rears that were off brand housings were the same bolt pattern. deciding factor is will your axle splines slip into the rear Exactly. His measurement from the center of the rear universal joint however will suffice and either will slip into the housing but installing a single reduction into where an original dual reduction carrier once mounted will take driveshaft modification to lengthen and conversely the other way. Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment https://www.bigmacktrucks.com/topic/59993-b67-rear-end-model-identification/#findComment-438499 Share on other sites More sharing options...
Farmall1212 Posted December 21, 2019 Author Share Posted December 21, 2019 Which is better single or double? This will be a site truck in The mountains so the lower the ratio the better. How much newer of a rear fits? Do you think the newer style that drop in from the top would fit if I changed the whole axle? I can get one of those cheap. Not looking to put a lot into it. Quote Link to comment https://www.bigmacktrucks.com/topic/59993-b67-rear-end-model-identification/#findComment-438508 Share on other sites More sharing options...
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