Munci oil change.
 

I have a 68' with the 327/300 h.p engine.It has the Muncie 4spd It doesn't leak but I have never checked it. I have heard there is no drain plug on the Muncie. I figure after 50 years in there it would do no harm to change the fluid.

No drain plug
 

Love this thing, Oil extractor.

...one of the best & cheapest pumps to use is a Mercury Mercruiser lower unit fluid pump. I've had the same one for over 20yrs, use on my boat's lower unit, C3 differentials & manual transmissions without bottom plugs. I think they are around $18-24 now, but well worth it. Mine is. They were designed to pump 90w gear oil. I believe I just have to put a longer hose on the suction side as it comes with a hard plastic tube that draws oil out of a 32oz bottle. I just slipped a longer 12" flexible hose over the tube.

There are several cheap suction pump options on Amazon. I picked up one of these for $15-. I've used it a few times, once to get the last of the sludge out of my B&W Super T-10 (which, thankfully, does have a drain plug to get the worst of it), and once to clean out a differential.

When I bought my '72 the muncie had a lower drain plug, but the thing shifted like a truck, hell with that, I drained the old crap out and loades it up with engine oil....straight weight, can't remember what it was though...30/40/50?? anyway, it shifted slick as snot....
I think I put some ATF in there too.....ran it on freeways and around town for a few years.....

would have kept it if I could have easily gotten an overdrive in it....

After you drain it, take the time to read this
https://www.widman.biz/uploads/Transaxle_oil.pdf
then refill with this
https://www.napaonline.com/en/p/SLRSL24239

https://cimg5.ibsrv.net/gimg/www.cor...c47af4cf44.jpg

Yeah, well I will admit to weakness. I wanted it changed but realize I will probably never do it again. so I took it to a trusted shop. The guy that owns it has had his own C3s for many years and I've known him a long, long time. We sat there and chewed the fat while a younger guy did it up on a lift in a few minutes. AMSOIL 80W90 synthetic gear lube. Only thing other than the required inspection I've paid anyone to do and for $40 bucks it was well worth it. I'll probably have him do the rear end too.