I've owned a '77 B300 van since 1986. It now has over 300K miles on it. Recently it started leaking so bad it was growing mushrooms on the carpet. Body cancer too bad to bother repairing. Engine and transmission have only 50K miles since complete rebuild. I also have a 76 Class "C" motor home on Dodge 1 ton van chassis.

To replace the '77 B300, I just bought a very clean '85 350 Ram Van with (supposedly) only 77K miles. It runs and drives great, but rear end makes a lot of noise. I haven't investigated the noise, but suspect gear and/or bearings. I also hear brakes scraping.

I'm removing all useable parts from the '77 for use in the '76 and '85, including the engine and transmission. They are all 360's. Then what's left will be scrapped.

My question is; would it be easier to just use the complete rear end out of the '77 in the '85 or rebuild the existing? I'm assuming they will interchange. The '77 differential is quiet, except for a clunking when backing up that been there since I've owned it. The brakes in the '77 were replaced recently and wheel cylinders were rebuilt.

 

On your new 85 have you check the rear brakes? Since you notice a scraping sound you might find that replacing them and maybe the springs may clear up the noise completely.

On the axle swap the 77 should interchange easily with the 85 though you might find that the axle ratio may be different. There should be a tag on each one that should have the ratio number.