Help! Clutch problem.

[kweimer]

I have just replaced the manual transmission on a 1973 220D with one from a 1970 220D (PO had let transmission run dry due to a leak at bottom bolt that holds exhaust bracket). Now the clutch slips badly in 3rd and 4th gears and especially up hills. I noted the bellhousings were a little different (appeared to be minor) and that the part numbers were different: The 1970 p/n 115 251 13 01 and the 1973 p/n 115 251 16 01. Is there a dimensional difference in these bellhousings that would prohibit interchange? Clutch driven disk showed very little wear and the pressure plate looked good. I retained the original slave cylinder so as not to have to bleed the clutch hydraulic circuit. Any ideas, anyone?

Ken