You may have already tried this approach, but I suggest it as it's something I initially overlooked myself. Vicegrips are a great fix for the right situation, but the niftiness of the way they work--a portable vice right in your hand--can lure you into overlooking their limitations. They are generally short-handled, a good thing in the right situation, but that limits the leverage you can apply with them. With a longer adjustable tool like a monster set of Channelocks, not only can you apply more leverage to the stuck fastener, but, more importantly, the longer handles allow you to apply more gripping leverage to the jaws on the fastener. Vicegrips are neat but deceptive in a way. It's easy to figure that once you've got the tool locked on the fastener, that sucker aint coming loose. But the short handle of the tool limits how much gripping leverage you can apply to the fastener, and some of that gripping effort goes to overcoming the locking detent in the tool itself. Longer tool, more gripping force and more leverage to turn the fastener. With an M46, clearance around the filler plug from below is not a problem. My suggestion would be to try once more to get the original plug loose with a better tool. My big Channelocks must be at least two-feet long. With a bigger tool you could apply a several times the force you can with a pair of Vicegrips, as cool as they are. Let's face it, the filler plug is probably pretty ugly already. Even a pipe wrench couldn't make it much worse. If I couldn't come up with monster Channelocks, I might even try a long pipe wrench--major grippage and leverage. You won't have to turn it far to get it loose, then let the Vicegrips take over.

Good luck with it!

rusteebrick

Would you be able to drill a hole in the fill plug? Fill the tranny, then stoppper/plug it?
--
1980 245 Canadian B21A with SU carb and M46 trans in Brampton, Ont.

Have you exhausted all the options for the fill plug that you reported was "stripped".

Until I replaced my M47 a while back I had to fill mine through the drain plug. I used a siphon gun (harbor freight) and a rubber stopper. I went to the local hardware store and purchased a black rubber stopper that was smaller at the tip than the drain hole and larger at the top of the stopper. I drilled a hole in the middle of the stopper slightly smaller that the siphon tube on the gun. The inserted the tube into it. I used an amount of tranny fluid slightly more than is required in the specs. This way when I removed the stopper, the amount I lost in the transfer of the drain plug was compensated by the excess. Granted it is a messy process but it works. Remember to have the drain plug in hand when you get ready to remove the runner stopper..And a lot of oil zorb...Max:>)
--
Max..1989 244 DL 5 Spd., V15 Phase II Cam Bilstein HD, Turbo Swaybars, Poly Bushings all round, Turbo Wheels, Black leather interior, Electric mirrors, LED dash and gauge lights and now NEW ECODES with the turn signals, 1992 black 244 next project

my 2 cents
Hi I had asked this q few days ago for m47 . The tapering barbed piece can work well. I achieved that with paper tape wound around pipe.The tape was so good that it has not pealed off even after filling

I got a 6' 1/2"OD pipe .put paper tape in a tapering fashion 3-4" from one end to make it slightly more thicker .The hole is slightly bigger. Put that end into drain hole (3") left it there There was minimal leak .1-2 drops a min. The other end was sealed into a cap of redline bottle . Then it just sat on driver seat holding the bottle upside down . I also cut a hole it to bottom for pouring additional fluid.

I had tried to reach the reverse light switch plug through gear lever opening as I had removed the lever for bushing replacement . It is very difficult unless U lower the transmission. And if u want to go from below the car .The space is v tight .My hand only reached wires.