BJ42 & BJ73 Gearbox xfer interchangeability

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Mar 18, 2013
Hi guys,

My gearbox in my 42 is crunching and transfer-case leaks quite bad..

I have access to a gearbox and transfer case out of a BJ73.

Was wondering if both 5 speed gearboxes are interchangeable? Will there be any mods I need to consider?

Moreover, assuming the transfer case in the BJ73 is all manual and not vacuum operated, can I put that into my BJ42 as well? Would this be the case if it was vacuum operated?

Im aware that the input shaft is the same as they both share the 3B engine, but finding it quite hard to get more info.

The split transfer case should be interchangeable, there were some flanges in some of the gear that made it harder to mix and match the old stuff and the new stuff but the output out of the transmission should be the same. The mounting bolt pattern is the same and the output shaft spline is the same.
You can transfer the vacuum actuators over from one to the other so that it maintains the same setup.
What years are they?
The BJ73 likely has the aluminum bell housing. You would need to swap your cast iron bell housing from the BJ42 over to the H55 from the BJ73. They have a different starter orientation and slightly different engine angle.

The top plates are different too. Don't know if your H55 was the correct 40 series type or if you have modified your floor to accept the 60/70 series style. The top plates are interchangeable so if you have a 40 series top plate you can put it on the trans from the BJ73.

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