Hi geezer

The box you have has a SIII number, so likely a SIII box.

The SIII a suffix were the weakest of the SIII boxes, especially in the case over the reverse idler.

I ran a 253 V8 on a suffix H SIIa gearbox for a number of years without any breakages. Probably because in the V8 you can idle up obstacles that others have to put the boot in and that is when you break things.

In a SIII box the 1st and 2nd gear are quite narrow and therefore susceptable to failure, so if that's what you have drive carefully in 1st and 2nd gear. In fact there may be times when its preferable to use 3rd and 4th low range instead of 1st and 2nd hi range.

Diana