I have a spare working block heater from my donor motor sitting around right now. Is it possible to install that block heater into the rearmost welch plug on the pax side of the engine, between cyl 5 and 6? or is the OEM block heater location machined differently to accept the block heater?

I think with dual block heaters and a pan heater I might actually be able to not be torturing the truck should I get it sealed decently before winter comes proper. I can't afford a webasto/espar/proheat right now (1200 bucks new, no idea what they go for used, probably not much less) so that's kinda my option.

Believe me, I'd LOVE an espar.