Woolls

Hello - I have a 987 Boxster 2005 3.2S, about 110k miles. It runs very well, I love it but it’s coming undone. The least of it is a an oil drip - maybe RMS - and the worst of it is the auto transmission. Shifts have become hard, jerky and revs climb and fall by randomly by around 200 RPM (+/-) while it’s cruising in top.
A good indp. garage has given it a full service, including a transmission flush that made no difference. They would like it back in again to further diagnose the oil leak and transmission woes. There was no evidence of metallic flakes in the engine oil, but in addition to the oil leak and phantom shifts, the transmission also seems to make a whirring noise that’s not right. I feel I’m heading toward the transmission coming out to be rebuilt, and an attack on the RMS and possibly the IMS.
Anyway, very surprisingly, another transmission has popped up locally at a very good price. It’s also a tip/auto from a 3.2S, and was performing well in a car that had covered only 30k miles. But it was a 986 and not a 987.
Q. Does anyone know if the 986 unit will fit into a 987’s shoes as a cheap and quick alternative to having my trans rebuilt?
Many thanks in advance.