Gearbox suffix

Hi, my series 3 g/box has failed and I need to source a lay shaft but I have to know what the g/box suffix is. Where do I find it?. It is a series 3 box in my 2a so no idea of the year. There is no ident tag on the bell housing.
The lay shaft bolt came loose and the subsequent end float damaged the shoulder on the splines.
Has any one had experience of the lay shafts from craddocks? seem a bit on the cheap side to be any good.
Any info / help would be appreciated.

Thanks for that...No visible stamping on the gearbox though. Sods Law!

is there a stamp on the transfer box? On one of the boxes Ive got, the number is marked on the side of the main gearbox is raised lettering.

Ive got a layshaft from craddocks, its britpart. Didnt fit it in the end, found my old one was good enough to reuse so keep it as a spare

Teeth on first gear. 35 is b or c. 31 is c or d.
If its 31, you're laughing cos the layshaft is the same for c and d.
Tricky for a and b as layshaft is different. If the reverse idler runs on a plain bush then it's an a.
Probably are other differentiations but you may have to wander through the parts book to find them.

Getting technical now, I have a bush on reverse gear not a needle roller. 31 teeth on first gear mainshaft and 13 teeth on layshaft. 21 teeth on reverse gear

This is the other problem, lots of gearboxes have later parts fitted although usually reverse is updated.
Are the dog teeth coffin shaped or parallel sided? If coffin then it's a d. Since you have a 31 tooth first then you are probably c or d don't know why reverse has been fixed though.
If you have the choice update to d parts. (if compatible)

springdon,
There is a lot of wear on the synchro teeth but I am sure they are parallel. So the 31 teeth on first means it is not a suffix A ?

ossie said:

springdon,
There is a lot of wear on the synchro teeth but I am sure they are parallel. So the 31 teeth on first means it is not a suffix A ?

Click to expand...

31 tooth first means it's a c or d gear. This also means its a c/d layshaft. Parallel teeth indicate a c.
BUT plain bush reverse idler was a only. So that's confusing.

My suggestion would be a c but I don't know how to definitively prove it. Depending on how rich you are, one idea would be to buy a Britpart first (frc2056 £23ish) and compare tooth profile to confirm.
Don't put the Britpart gear in the box for gods sake. And don't to forget to replace the syncro cones.
Good luck.

Thanks all for the info.