Will a ‘98 8.3 Cummins drop in to replace a ‘94 8.3 Cummins? Both are mechanical fuel pumps. Or can anyone point me in the right direction?

The ‘94 is
Family: 413B
CPL: 1262
Model: C8.3-275
Engine #: 44944411
Ref #: S01-22436-000

’98 is
Family: VCE50536
CPL: 2103
Model #: C8.3-250
Engine #: 45595291
Ref #: 1759091

 

If they are both on-highway engines with the P7100 injection pump, then you should be able fo make the swap. There could be differences though in the air compressor type, flywheel housing, etc. depending on application. For details like that you will either have to compare the engines side-by-side or find a Cummins dealer willing to work with you.

There were soem off-highway 8.3L engines built with a different bosch inline pump. Don't remember what the model was, but the differences are obvious if you compare to the on-highway P7100 pump. So an off-highway engine with this pump will be a no-go unless you're willing to swap out the camshaft, gear housing, injection pump, fuel lines etc. from the old engine. Not a small job.

Also the 8.3L engines put into Ford trucks had some odd ford-specific changes... even a different cylinder head casting for better clearance in the Ford chassis. Not aware of any ford-specific changes that would prevent a swap, but something to keep in mind.