i dont know about Kent, but i can recommend CTS in markyate in hertfordshire. (assuming they are still going). they know how to properly refurbish an RST box.

some places turn down the taper on the mainshaft, and then insert a sleeve over this that fits into the standard box bearing, this is bad as it means the shaft is only as strong as its cross section which has been reduced making it weaker than standard!

the correct way of doing this is to purchase a new shaft and machine the casing to accept a bigger bearing, this is around £600 exchange, then ontop of that you have shot peening gears, and different diff options......depending on budget.

call bernie though, he knows his stuff!

www.gearboxman.co.uk

http://www.gearboxman.co.uk/psgearboxes.html#03