[THEFERMANATOR]

How does your current 3.7L mount in? Some have a single mount and some have a dual mount. The 4.3L will mount in like a V8 does if you use a new style 4.3L. The older 4.3L's used the same bellhousing and couplers as the V8's whereas I have seen that the newer ones use a bellhousing and adapter that moves the engine forward some. SPARE will be able to confirm all the differences as he is the I/O guy. I just do them as a hobby mostly. Also watch EBAY as new style harnesses can be had fairly cheap from time to time. You can use the early harness on a late engine, there is a pin change in them around 87 or 88 regarding the alarm circuit, but you can get around that. All of the 4.3L's I have seen use either a 1.65 or 1.81, and IIRC the 3.7L uses a 1.81 ratio(some had a 2:1). I see 3.7L's on CRAIGSLIST down here in TAMPA for under $1K about once a week still running.