A: Speaking of bridged rocker heads, I have one from an '80 258 for sale. It is in need of work as it had 100,000 miles on it, but it's the last of the tin valve cover motors (cover included) Motor had tossed 2 rods, but was still running when pulled. (block was ventillated) From: farna@xxxxxxx Subject: Re: Rebuilt Engines on eBay To: mail@xxxxxxxxxxxx Message-ID: <ADVANCES6267yRLVbND000007fb@xxxxxxxxxxxxxxxxxxxxxxx> The trans bolt pattern on the back of the block changed in 1972 to the same as the V-8. 71 and earlier sixes used a smaller bolt pattern. A 258 was made with the small pattern for 1971 only. Any of the 64-71 199/232/258 engines will bolt right into the 66. The head off your 66 will physically bolt onto a 1974 and later six, but you would have to install an external oil line to feed the shaft rocker head as the block for the later engines don't have the internal oil line drilled. It would be much easier to buy a junkyard 258 bridged rocker head. You CAN use a bridged rocker head on the older engines, just use the correct length hollow pushrods. Around 72 AMC came out with the bridged rocker (studs mounts) head, but due to a patenet dispute w/GM went back to the shaft in mid year and through 73 until the dispute was settled, then back to bridged rockers. So you have to remove the valve cover. If using a later model head there's no reason to use the shaft type, which is known t! o have oiling problems. Just watch combustion chamber size, as that grew over the years. A later head may not have as much compression as an early one. You might be better off to rebuild the 232 you have, as good running pre 72 engines are hard to find. Someone on the list may have one though.