I think my 727 is fried. Now I'm at a crossroads...

Righty Tighty said
I installed the deep pan yesterday and took another look at the cooler line. It wasn't quite as sharply kinked as I originally thought -- in fact it wasn't kinked at all -- just a sharper bend than previously. I was careful to not overfill the fluid and took her for a test drive. Drove fine, shifted fine, no leaks after about 25 minutes of city driving.

Thanks for all that info. With what you've said in mind, I feel like I'd like to pull it out and rebuild it. It's not hard and I would have peace of mind knowing I freshened it up. Although, the valve body does intimidate me...

The car sat for 20 years before I bought it, and I have no idea how the previous owner cared for it.

You mentioned ATF+4? I'm guessing you prefer that over Type F? I've read of folks using Type F to help with firmer shifts, so I've been using that for a couple years. What are your thoughts?

I'm not against Ford ATF specifically, it is very useful in Fords and in some race built transmissions of all makes if the friction materials in them are designed for it. However, if you build a TF with OEM type clutches and bands you will find the more viscous type F will prolong the engagement time of the friction surfaces, but sometimes increases the bite once it is squeezed out. Automatic transmission shifts are a timed event where one friction unit releases as another one engages, thus viscosity and friction modifiers in the fluid affect that timing. Mopar specified fluids are a bit less viscous and squeeze out of clutch packs and band/drum surfaces a bit faster, and the synthetic +4 is the best yet as it is a bunch less likely to be ruined by a bit of excess heat, has superior lubricity, and squeezes out faster. It is a "fill for life" fluid in most circumstances. I'm finding the +4 is quicker and more responsive. Regardless of any of that the use of type F fluid isn't/wasn't the cause of your fluid puke problem, that was and may still be caused by some other factor. Using the deep pan and running the fluid level a quart low on the stock dipstick might well solve the problem for good. I do wish you the best of luck!
Steve