Trying to sort out my "new" 64 Dynamic 88 coupe. Does it have a TH 400 or hydramatic, and is it a 4 speed? One post buried deep in search said all the big Olds had 400 starting in 1964, and slim jim ended in '63, any truth in this?
I keep waiting for that shift into 4th and it never comes.

 

I don't know what post you were reading, but that info is incorrect. The TH400 was never built in a case that bolts up to the 394 and was not factory installed in Oldsmobiles until the 1965 model year (when the second-gen 425 replaced the first gen 394). You have a slim jim.

 

Thanks Joe, is it true that the 3 to 4 shift is around 65-70 mph?

 

Only at WOT in DR or in S. In Dr it will shift sooner depending on throttle. And technically the Slim Jim is a 3 speed, with a pseudo shift from the converter's accelerotor.