Please pardon my woeful lack of knowledge, but is there any practical difference between a WM20 and B31/33 sub-frame? and while I'm here, does anyone in the USA have a rigid sub-frame for sale?
Yes.
The M frame is a heavy eight frame ( very heavy ) and the B frame is a medium weight 'sports" frame.
Lots of little things like bolt holes in different positions.
Having said that you can swap the engines, you just need to make up new engine & gearbox muonting plates.
I have tried fitting a plunger B series rear to an M20 front they are different heights and won’t bolt together .I also found that the gear box plates are a different length .
I have tried fitting a plunger B series rear to an M20 front they are different heights and won’t bolt together .I also found that the gear box plates are a different length .
