I had failed to mention that the GM 2.5 also came in Jeep products until the early 80s. Then AMC-Jeep went to their own 2.5 engine. In my opinion, the 2.5 is a better choice as it allows the use of cross-flow heads where the 153 and 181 has a high-mounted distributor. GM-Pontiac still offers performance aluminum heads made by Brodix and an aluminum manifold.
I've also got new and used parts along with access to two Pontiac Superduty performance engines. One is all-aluminum and the other has the iron SD block with aluminum head. Both are 166 cid. You might be surprised at the reasonable cost of Superduty parts and older engines. Send me an email if interested.
Gerry
dedonis@kans.com
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