Thread: series 1 gearbox options

I have a 54/55 series 1 that is still under a prolonged rebuild. I finally fired it up the other day and the gearbox I thought was fine turns out not to be.
I have read articles where series 3 gearboxes with sincro are swapped in or series 2 are stronger. I am not keen to go as far as modifying the firewall to accept pendant pedals to align with the clutch arrangement and was hoping to bolt something in. Extenally all the series boxes look the same to me from a novice perspective, so I was wondering on the interchangability.

I was thinking my options are to rebuild the series 1 box (there was a H stamped into the side, so I am not sure if this means it is a suffix H)
or
Install a later series box and swap the bellhousing from the series 1 if required/ possible to keep the same clutch set up ( the clutch is new and I was keen to retain this).

I have seen later model boxes go fo a couple of hundred and was thinking this may be a more economically viable option. The motor being mated to is the standard IOE 2 litre motor.

Interested to hear what is achievable as a bolt in swap without modifying parts.

Thank you for all your constructive replies and thanks for the offer Jon. Sorry about the delay in replying as I had a couple of days on the outskirts of the Riverina and to say there is not much internet coverage out there is an understatement.

I have been able to track down the source of the gearbox issue. When I started the project I collected 2 dilapidated vehicles from the owner (1 running on abuse and neglect and the other as a parts vehicle with a seized motor though pretty much complete). I was told at the time the better gearbox was the one removed from the parts car though he had not finished transferring it and it was sitting in the rear tub. This was the one I installed. After firing up the vehicle for the first time in a couple of years the motor wanted to stall when a gear was engaged and the clutch released. Removing the gear selector cover on the top of the gearbox and comparing the two gearboxes, I found that someone had opened up the case had a look and not put the selector fork back over the gear cluster properly. This meant that the vehicle was trying to select 2 gears at one time. With the fork over the disc it now engages all gears and feels pretty right.

Still yet to drive it as it is on stands, though it seams closer with it now running and selecting gears.

I guess most people go through this thinking with a rebuild with slotting later model parts in if they appear the same and offer better reliability or function in service. I am happy to keep the original model gear box in and might have a go at refurbishing the other one with new bearings, gaskets and seals. This way I will have a quality spare if ever required that I know the history of.