I have replaced all 6 side plugs, in-car ,on a hoist. I don't recall it being that big a deal. They rot, or seem to rot, from the back of the engine to the front. For me it's always been the one behind the starter that goes first.You can even punch them into the engine and leave them in there for the winter.Then, if the thought of one or two of them being left in there bothers you, you can yank the the engine out later when it's more convenient. Altho getting them out is not usually the hard part. Cleaning the holes, and Driving in the new one straight, is the tricky part.
To clean the holes in-frame,I use a right-angle die-grinder with a wire-brush insert.
I buy a couple of extra plugs just in case I drive one in too crooked to reuse. If they go in too crooked, I drive them in all the way and pull them back out, and throw them away, they're gonna be leakers.When installing them, I start with the hardest-to-reach ones, that way if I have to remove one,and if it's reuseable,I can stick it in the easiest-to-replace hole. To help install them straight, in the hard holes,in-frame, I get the type of plugs with the deep sides; they tend to steer in straighter;but they usually take a bit more force to drive in. I seal them with IndianHead shellac;in the hole and on the plugs. Very messy,very sticky, and very good seal.The IndianHead acts as a lubricant during the install,yet sets up in a few hours. Just let a little time go by before you put that mega-psi cap back on.
Do not pound them in with too-small a socket. While it's not likely to damage them, they will get looser if the center is stretched inwards. Plus you can steer them better with a socket the fits out near the cup edges. They do make a nice driving-tool with a bent end, to use in a tight spot.
I run a 7psi cap,year-round. My rubber parts last for decades, and it's easy on the heater-core.
If the back-side ones are already leaking, the ones in the bell won't be far behind. They sit a little higher in the block I think, but it it ain't all that much. But you just never know; they might already have been changed,lol. I sure wouldn't pull the trans to look, that's for sure; I'm lazy that way,and getting lazier with each passing year.
