2nd Gen 3.9l used as short block for 1st gen
Champion
Joined: Jan 2013
Posts: 4,737
Likes: 374
From: Northwest Louisiana
LA intake won't bolt to the Magnum heads without redrilling. Youi'll have no EGR nor heat-bed to keep the air/fuel mixture warm for better vaporization.
The LA heads will bolt to the Magnum block, but the rockers won't last due to the lack of the oiling passages.
IOW, not as easily as rebuilding your current carb'ed LA block.
Now, if you find a 91+ donor truck (91-96; 96 has a slight uptick due to being OBDII), and use a manual ECU (since the 87 is either manual, or 3 speed auto), you might be able to upgrade to a full Magnum truck. You want the donor because you'll just about need all the wiring ...
RwP
The LA heads will bolt to the Magnum block, but the rockers won't last due to the lack of the oiling passages.
IOW, not as easily as rebuilding your current carb'ed LA block.
Now, if you find a 91+ donor truck (91-96; 96 has a slight uptick due to being OBDII), and use a manual ECU (since the 87 is either manual, or 3 speed auto), you might be able to upgrade to a full Magnum truck. You want the donor because you'll just about need all the wiring ...
RwP
tyvm. Seemed like a good idea.