What's the difference between 6.2L engine #14022660 vs #12552929

[BITS1611]

Good Morning. I'm new to this site and forum however I've known this site for 20 yrs. I bought my 1st diesel back in 2001 1985 Chevy K20 (6.2L) "J" code which I only enjoyed driving it for 9mns and broke down. After 19yrs of sitting I decide to bring it back to life (yay). I need some help here I recently bought a completed drop-in from a guy who didn't want the engine for $250, I’m not 100% sure if it was a "J" code, vin # was remove long ago off truck.

What's the difference between my old 6.2L (14022660) and new/used engine (12552929)?

I would like to still use my current transmission and transfer case if this new engine works. Any help you guys can give me is greatly appreciated. Thanks Bits

[BITS1611]

How could I confirm if engine is a "J" code, if VIN number is not available?

[DmaxMaverick]

Welcome aboard!

You'll find the info you need in the 6.2L/6.5L Diesel - Upgrades & Service (https://www.thedieselpageforums.com/tdpforum/forumdisplay.php?f=22) Forum. The 6.2/6.5 Cylinder Block Date Code (https://www.thedieselpageforums.com/tdpforum/showthread.php?t=24325) thread describes the differences in the blocks, and when they were available.

There is no difference between C and J code engine blocks. The difference is the intake and emissions systems, and in some cases, the heads (not significant). If the intake has EGR, it's a C code, and the original fuel injection pump would have been calibrated for slightly less power (a simple adjustment). The intakes are interchangeable within the vehicle models. A van or HMMWV intake will not fit pickup/SUV heads (the bolts angles are different). Chassis models can vary, depending on application.