Both the 265 and 280 are rebuildable and BMW is a source for the internal parts(if they are not on backorder).You guys lost me! So the getrag 280 (which is in my '91) is not rebuildable?!
My understanding was that the 265 was compatible with the 280 as a replacement for it. It looks like metric mechanic only offers the 265 which they indicate is the replacement for the 280.
But then again, metric mechanic seems like a tough outfit to get a hold of.
The 265 has a lower 1st and 2nd gear than the 280 and is better used on M5's with the 3.73:1 LSD as I don't think the M5 with 3.91 can really use a lower 1st & 2nd gear.
However, in any even the 265 has a bigger gearing gap between 3rd & 4th than the 280 which is what an individual that I know didn't like about the 265 transmission inadvertently swapped by an indy into his E24/M6.