I've just had a reverse sprocket cut by my local laser cutters. I got the plans (dwg) from another post on here.

Really happy with the quality and cost. £4.28 inc VAT! (10mm mild steel)



As it was so cheap, I'm thinking about having the rest of the sprocket adaptor cut by them.

a bit like this -



to end up with something like this




Off the shelf sprocket adaptors are about £85 inc P&P.
I can probably get this cut for less than £10.


As I'm building a sandrail, the engine is directly mounted to the diff. There is no UJ between the two, so alignment is going to be quite important.



also I dont know if the off the shelf parts are hardened?


[Edited on 5/12/16 by nick9one1]

Yes the sprocket adaptors are hardened (the ones from Talon certainly are).
Without hardening the splines will no doubt just rip out.

You can get away with a laser cut gear for your reverse as it sees a lot less stress on the teeth and is only used occasionally and does not have a gear constantly meshed.