How do I find out if my 01 325i 4-door has a M54 or M56 motor?

I am replacing the clutch in my 2001 325i 4-door with 5-speed and I thought it would be a good time to replace the rear seal but Pelican parts lists seals for the M54 and M56, I thought I had an M56 but now I'm not so sure.
I did a lot of searching but can't seem to find it anywhere! I'm sure it's staring me right in the face but I just can't find it!
Anybody help?
Also, this is a clutch question but I read that you need a 3 foot long bar to reach the tranny bolts, I was wondering if it would work to remove the cabin filter to reach them?
Thanks in advance.

You have the m54 since your car is a 2001 and a manual transmission. The m56 was only in automatics from 2003 to 2005. Also the model would be 325iA

As for the tranny bolts, to get those ones on the top side you need to take out the cabin filter and remove the plastic tray it sits in. I think it takes 3 or 4 torx bolts to remove.

For those who come across this thread while searching (yeah right), here is a picture incase you don't know:

Thanks guys, now I can complete my order!