Re: New to site with looking for help!!!
OMC used an electronic shift assist module (ESA) that "stumbles" the ignition to cause the engine to shudder (try to stall briefly) and allow the lower directional gears to disengage from the dog clutch when shifting to neutral (and the ESA also could do this going into gear, but that was less important).
Your 1988 4.3 would have had points ignition and your ESA module (if it is original and still there) is only compatible with points ignition systems.
If you end up going with Delco or other modern systems, you can modify the ESA system to work more like Mercruiser's "shift interrupt" system, or you can buy a new ESA from Rapair/CDI corp that will be compatible with most any 4.3 marine distributor you can find - points or electronic.. the CDI ESA is about $90 or so
Mercruiser style shift interrupt is a popular mod for OMC's but you lose the stumble into gear, as the Merc design only stumbles coming out of gear...which is fine.
