My '83 wagon (M46 manual 4sp +OD) sounds awful in the rear end when pulling in 1st gear. I'd like to replace it, but don't know the ratio or what other models are direct compatible.

I have a '90 240 DL wagon (automatic) that I could pull from, if it works.

 

The '83 has an M46 manual and a 3.31 rear end. I found a 3.73 (?) from an '83 240 automatic. Should I go this route? What are the downsides? And how difficult is this to do? What about the speedometer?

Thanks,

 

It is a direct swap and will lower your mpg a little. However, it has been the ratio of choice with M46 240's for years. As for the speedometer, it will be incorrect...assuming the M46 in your car is original. Typically, the 3.31 was used behind the M45 non-overdrive tranny. When you unscrew the speedo cable there is a small gear that is easily removed and is what controls the speedo output. If you could find an M46/3.73 at the jy you'd be good to go. The later cars 84+ almost all had M46 overdrive trannys w/ 3.73 axles. There is a label on the drivers side axle tube on the back side that states the ratio. Usually covered with road grunge oil and undercoat, you can clean it off gently w/ a rag and brake cleaner. If you use carb cleaner, it will wipe off the print and leave you w/ a blank label!

 

BEfore you go pulling drive shafts does the car shake violently? IF you're coasting does it make noise, or just under acceleration. Going to that drive shaft you will get better gas mileage, acceleration will suffer.

 

adub96 - the car doesn't shake much, but it's definitely only when pulling in low gear. It cruises fine.

swiftj - now you've got me wondering. I read the label on the axle and it is a 3.31. How can I check the transmission type? Is there a label somewhere?

 

1030 and 1031 are the two rear awxle types that may be in the car, 1030 has a single side rib while 1031 has two side ribs. They have different sized input shafts but i'm pretty sure thats about it.

Before swapping rear axles you should rule out the rear universal on the drive shaft. When they start to go they tend to do that same thing.