Older O/d tranny vs. newer

Will an early O/D tranny bolt up to a newer engine. In the midst of putting a newer "hotter" engine in my 72 B. The engine doesn't seem to want to go onto the tranny before I pull it back out does anyone know if theres a difference between the later od tranny and older one (pilot bearing diameter, shaft length?). Have the O/D tranny that came with the engine just got lazy and was going to leave the older O/D tranny in but may have a problem. Whats thinks the group?

methinks it would be good to define just how old is this older transmission? is this a 3 or 4 synchro model?

They're both O/D's older is a 72 (if original, at least thats what the car is) newer not sure but had to change out the front plate to go in the car as the motor mounts where diferent. Thanks Bill

If your "old" unit was a 4-synchro gearbox, and the "new" unit is also 4-synchro, they should both be the same as far as bolting it up to the engine (are the rear engine plates the same?).

The change in the front engine plate indicates the "new" engine is from a RB car.

RB, car? I checked on the other couple B's in my shop, looks to me the plate is just a change made when they redisigned the motor mounts. I pulled the engine back out and despite cleanning the clutch spline it seemed a little rough. Filed the splines with a jewlers file and wire brushed the heck out of them. The clutch aligment tool was quite a bit tighter in the newer engine then the older so more cleaning of the spline was still tight put the engine is now in and on to the rest of it. Can't wait to hear the cam with the cross flow head and pecco exhaust. Should run a tad better then my TD (lol). Thanks Bill

See my Trader ad...I have a black OD that won't work for my '80 so if anyone has a blue label OD willing to trade, I am all ears....

In some cases what seems to be the easy way is actually the hard way ! !
On MGs the trans /engine is easier to pull,,reinstall as a unit .

The black label OD's will fit on an '80 engine. Kathys B is an '80 and I jsut got done installing a '72 black label in it. I did of course replace the main tranny case with a side fill case from a '77. But as far as not fitting....didnt have a problem.