i have a 91 3.9 in my dakota. using oil, and is pretty asthmatic after 200K. so i bought a '92 dakota to use as a trasplant donor. pulled the motor and tranny. did not realize that there were so many upgrades to the '92. the heads were cracked. i don't have a kegger intake nor do i have the same type of injection system. now i'm wondering, will the '91heads fit the '92 block? the block codes are different, but is that because of the heads? or is there something else such as camshaft, cam bearings, crank bearings, seals, etc, etc?

is there anyone out there that can help me with some of these questions?

 

The heads will work but the your stock intake manifold will not fit. Unfortunately it sounds like your stuck unless you wanted to use the electronic fuel injection system off of the 92. I would take a lot of time but it would be a stronger engine and better fuel economy.

 

i realize the heads don't swap. and i realize that the intakes, tbi, etc, are matched to the heads.

but what of the blocks themselves. are they the same in spite of different code numbers?

can i put my distributor, TBI, intake manifold, heads, exhaust manifold from the '91 block and use them on the '92 block?

i realize the injection system and intake on the '92 is better, but i don't want to swap out the wiring sytem not to mention having to buy another ECU and all the crap that would have to go along with that. ie; mass air flow, oxygen analyzer, exhaust, catalytic converter, water pump, engine accessories, etc, etc, etc.

i just want to know if the blocks are essentially the same.

 

As far I as I know, yes it is. There were upgrades but if you keep all the internals you should be okay. There is a good write up you may want to read under the FAQ2 it has to deal with v6 to v8 but it does talk about the differences inbetween pre magnums and magnums. Also www.alpar.com will have tons of info on the engines.

 

can't thank you enough for your help....you've shortened my search up drastically, not too mention a butt load of references and sites to search! thanks!!