Classic/Antique Car Repair: 1962 Chevrolet Impala, chevrolet impala, different shape

Question
Hi, Tazz - greetings from London, England.  I've just bought a 1962 Chevrolet Impala, four-door hardtop (bodied by Fisher).  It's right-hand-drive, and has the inline six engine with a two-speed automatic transmission.  The auto is giving me some trouble, and while I wait for my workshop manual to arrive I have a couple of questions for you: The car drives and shifts totally normally, but only for about the first ten minutes or so.  Then it stays in low and refuses to shift up; I've tried shifting manually (on the column), parking and re-selecting drive, etc. but nothing works.  I checked the fluid level initially - and it was almost completely 'dry' on the dipstick - and topped it up; now it's on the level and clean but still behaving the same.  It's like it's fine until the trans 'overheats' - okay when cold but not thereafter.  Any ideas?  Secondly, were these cars ever fitted with an auto other than a Powerglide?  I ordered a new filter and sump gasket, then crawled under the car to fit them and was faced with a trans that doesn't look like it has sump bolts facing downwards at all.  It seems to be a completely different shape to what I was expecting.  Any advice would be greatly appreciated, thanks.

Answer
To my knowledge this was the only tranny at the time. Does not mean someone else hasn't replaced it though. The Powerglides were good transmissions until they started having problems, and then it was nearly always a rebuild job. The valve body was prone to lots of build up and stuck alot.

You can try a good transmission flush, but don't get your hopes up.

Sorry, wish the news was better.