M925a2 Rear Main Seal

I have to replace my rear main seal on my 925a2. I have gone to the Cummins website and typed in my engine serial number. I see the part numbers for the seal and the gasket for the rear main seal housing. What I haven’t found on the Cummins site or looking in the TMs is the gasket that goes between the block and the flywheel housing. Does anybody know if these trucks use them? If so what is the part number? I do see a discription of a rectangular ring. (Part #12 below) Wasn’t sure what that does. Also if anyone has a recommended aftermarket kit for this job. Seems when I google Cummins 8.3 there’s a million 5.9 websites. Also since I have to remove transmission im also looking for the possible Allison bell housing gasket part number also. Or is there no such thing made by Allison. Thanks for any help.

#12 is plug. #3910248. Should be plastic

No block to bellhousing gasket. No transmission to bellhousing gasket

Do not put any sealant on either.

Thank you Wes. I wasn’t sure regarding the Allison gasket. This is what I found in Tm regarding m939 and m939a1. Part #1 is a gasket

Not needed.