Volvo Quick Reference Parts Catalog lists transmission mount for M45 and M47 as 1359138.

FCPGroton lists transmission mount for M45 as 1359138. They list transmission mount for M47 as 1273714.

Can I use the 1359138 mount that I already have on my M47? Excuse me for not crawling under the car and comparing but I'll be there soon enough.
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'80 DL 2 door, '89 DL Wagon

This is not an exact answer to your question, but the trans mount can be either round or square. One doesn't substitute for the other. If there are further variations I don't know about, this will be of little help to you. If you remember what shape your car's mount is, this may be your answer.

I had to get under the car last night to adjust the clutch for the second time in a month. This all seems to be heading towards a clutch replacement.
Anyway, I took a look at it and the square mount that I have for the M45 is not quite the same as the square mount that's on the car. Still it looks like it might work but I think I'd better get the one that FCPG lists for the M47 unless someone can say for sure that they are interchangable.
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'80 DL 2 door, '89 DL Wagon