Andrew is correct about the front left motor mount bolt hole being used for the knock sensor on Renix 4.0L engines. The standard car mount plate has to be drilled out and a metric bolt used (seems like it's a 10mm metric bolt, but it may be 12mm -- been a long time for me!). Most people, however, are using mid 70s-late 80s blocks. Earlier ones are a bit fewer and further between nowadays, most were made after the Pacer came out. I seem to recall that the boss isn't drilled and tapped on some blocks after 2000, not sure what year that started or if I'm even correct... all may be drilled and tapped, I've not actually looked at a 2000+ block. Newest I ever had out of a vehicle is 1999, and I believe it was drilled and tapped. -------------------------- Date: Thu, 10 Mar 2011 12:17:03 -0500 (EST) From:adh@xxxxxxxxxxxxxxxxx (Sandwich Maker) " From: Glen Hoag<hoag@xxxxxxxxxx> " " IIRC, there is at least one new motor " mount boss on the 1975-up block to accommodate the Pacer brackets, so " in that regard, the Pacer block was different, but once changed, the " same block was used on everything until the next change, which I " think was for the Eagle front axle mount. I think that extra boss is " where the knock sensor wound up on the 4.0 block. afaik it's one of the original amc mount holes; i've read several references to drilling the amc mount out to 12mm [the knock sensor thread] and getting a metric bolt. i believe the 4.0 normally uses new holes just fwd of the amc ones. -- Frank Swygert Publisher, "American Motors Cars" Magazine (AMC) For all AMC enthusiasts http://www.amc-mag.com (free download available!) _______________________________________________ AMC-list mailing list AMC-list@xxxxxxxxxxxxxxxxx http://list.amc-list.com/listinfo.cgi/amc-list-amc-list.com