I have rebuilt a series 2A suffix "E" gearbox. I replaced a worn second gear from a series 2 box (no suffix) - it jumps out of second gear.....
I have read that the ratios in the gearbox changed after suffix "B" so this second gear out of a "nil" suffix box will not work .... is the answer a second gear out of a later than "B" suffix box?

 

go directly to Land Rover Defender Forum - Defender & Series Owners Community . Do not pass go, do not collect $200.

We'd love to help, but in all reality you are much more likely to get a quality answer over there than here.

Good luck with the truck!