The 1992 you are considering would be a very good choice. The most important advantage to a 1994 and later model would be that they have the P7100 Bosch inline pump which is a more durable and more easily modified pump than the Bosch rotary pump used through 1993.
The automatic transmission used in the 1992 model is the A518 as opposed to the A618 in 1994 and later models. Both of these are 4 speed overdrive transmissions. The most obvious difference is that the A518 does not use a lock up type torque convertor. Reading posts in this forum it appears that the lock up convertor is the source of most transmission problems with the A618. For myself I am happy with my non lock up A518. I am using an aftermarket special convertor and I can tell you that it is very tight as far as slip. There are many upgrade parts available for either transmission that will make either of them work well for you.
The 1992 model does have a large 21cm turbine housing on the turbocharger. This large housing causes more response lag than the smaller housings. This is easily overcome with the installation of a rather inexpensive housing.
The 1992 model is aftercooled. I will probably get flamed for stating "aftercooled" instead of "intercooled" but these engines are not intercooled. The true definition of intercooling is the cooling of charge air between compression stages. The true definition of aftercooling is the cooling of charge air after the final stage of compression. Since these engines have only one stage of charge air compression, the turbocharger, they are aftercooled. If you look at Cummins model description of these engines it is 6BTA5. 9. 6=number of cylinders- B being the engine family series- T= turbocharged-A=aftercooled- 5. 9= displacement in liters. If they were intercooled they would not have the "A" in their description. There are some B series that use an air to water cooler mounted on the intake manifold. This is also an aftercooler since it is the final, if not only, cooler for the charge air. As I said, I will probably hear disagreement on this, but definitions are definitions.
All in all, if you can get the 1992 for a good price it will work well for you. I would be real careful to check the "attachments" such as vacuum pump, power steering pump, aftercooler, etc. for damage. Some of this stuff is expensive to replace. If you can get a 1994 or later for not too much more money, it would be a better starting point.
Good luck with your project!
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