Transmission compatability.
 

I am in the process of having someone restore my 1987 250 DL sedan, which I am original owner. Has been sitting in my garage for about 10 years waiting for this opportunity. I also have same model, but a 1991. I kept the 91 for parts but wondering if the two, 87 and 91 have the same transmission compatability. I was told many years ago that the 87 needed a new transmission so took it off the road. With a little pampering, we did at least get it started, same with the 91. I have a mechanic who is considering the project of restoring the 87 but needed a few questions answered. Thanks for any advice you may have regarding the transmission. Love my Volvo!

automatic transmission or standard?
whats wrong with the transmission?

250? that might be an excavator? did you mean a 240? lets assume it is a 240 or 245 automatic,,
in 87 it would likely have had a distributor near the front of the motor with a hall sensor but by 91 a crankshaft position sensor, that might not be such an issue, to avoid the electrical complication , I wouldnt' change the way it senses the crankshaft position. be aware that either system uses a different igntion control unit. If thats in the bellhosing maybe you can omit it and continue to use the distributor that came with the car,,
maybe you can get a picture of either transmission and any ID plate you can find on it.
I had one with an auto transmission , an 89, where the sprag clutch failed, it would disconnect and feel like it slipped out of gear ,reving feely. then suddenly reconnect with a loud bang and a real shock to the drivetrain,. It wasnt; so hard to replace it by removing the housing part near the first U joint. the sprag cluch is like a one way bearing , it locks in one direction and runs fee the other direction, uncommon failure. did not require transmission removal. also near it there is an output shaft seal , they may leak and spurt a bit of fluid but changing the seal is easy. Ive owned quite a few 240's and 740s but have had very few other issues.
I had one with a standard tranny. it had bad synchromesh, probably a previous owner wasnt; great at shifting gears so I drove it nicely, gently, matching my shifts, doubleclutching, and wore it back in, then it shifted nicely.

any one I had that had a standard tranny needed U joints and a clutch, throwout bearing , pilot bearing. maybe a clutch cable, they can stretch. often Id also do the driveshaft center bearing if I did the Ujoints.