This is an attempt to create a brief and basic list for US 240 power-/ drive-train interchange. I see this info in bits in the archives. Here's my summary (with some info from emails here) - please correct/ amend:

Engine: All red-block engines (76-up?) interchange but it's easier to stick to the B230F 85-93. Several main components are different eg. 89-93 cars have a CPS. If the recipient car is complete the earlier engine will fit with parts replacement.

Automatic Transmission: AW-70 1982-85 (also AW70L?); AW-71 1986-93; AW-71L 1989-93. AW-70s & AW-71s interchange but require the matching torque converter; and an __L trans requires an __L converter. AW-71 is stronger than the AW-70 transmission. AW-/BW-55 before 82? 740s have same transmissions? _L models not good in turbo cars.

Manual Transmission: M46 4-speed <= 1985; M47 5-speed 1987-93. Bolt-in swap but requires matching driveshaft (M46 shaft shorter due to OD).

Driveshaft: 83-93 interchange except as noted above. 244 & 245 are same length.

Bellhousing: 89-93 are notched for CPS but this notch can be made with a saw/ dremel/ rotozip.

Rear axle: All 83-93 interchange. Others? Gear ratios differ between 244 & 245 and between AT & stick.

Wiring harness: I also see mention of the "good" and "bad" wiring harnesses. The good one is 1986-1993 or is it 1987-93?

Not-200s: Various 7-series and 9-series parts will fit 200s. I don't know anything about these larger cars.

(My own focus is 86-93 although I have a few 83-85 parts cars. I try to avoid pre-83 CIS cars.)
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85-92 240s/ 245s - parts cars & drivers