My machine is one with a girder fork, however it seems to have a later model gearbox that externally looks similar to what we have on B31's.
I am let to believe that the gear ratios are same across M20 & B31's. Is that true?
What can i check to see if it is meant for a M20 rather than a B31?
Also would the Gearbox covers (inner and outer) of the M20 types fit onto the gearbox i have?

Thanks in advance guys - you guys rock. Would not know what to do without you.

email (option): imkalki@yahoo.com

Hi..The M20/21 B31/33 have identical internal gear ratios when the two types of box you describe are used. Military M20s use an 18T gearbox sprocket, all civilian models a 19T sprocket and the engine sprocket is changed for different models.
The inner and outer covers from the earlier box will fit onto the late type you have...BUT..there will then be nowhere to put the oil in.
Girder fork M20 boxes have a filler spout on the main gearbox case while later boxes are filled through the front cover, So, with early covers on a late case there is no filling point.. ...Ian

email (option): ian@wright52.plus.com

thank you Ian for coming to my rescue. shall share pics on the forum once she is up and done

email (option): imkalki@yahoo.com