Few Questions on drivetrain

As Ivy states, the Trak Lok limited slip was introduced into the Ford line in 1969. There are a number of aftermarket limited slip units patterned after the Trak Lok, and they are probably worth the money. As I understand it, the 8" aftermarket Trak Loks are of the 4 pinion style, while all original Ford units are 2 pinion. The difference is significant.
IMHO, avoid the early Equa Lok units, as they can be a real handfull behind a performance motor. As an example, Ford would not sell the Equa Lok setup behind either the HiPo or the 427 engines. The Shelbys were fitted with a Detroit Locker, not a Ford product.
Best,
Al

Since you are in the decision making mode with your project, I'll pass on a little hard-earned experience for your consideration. Don't, don't, don't even consider the T-10 tranny. There is almost no chance you will find one that won't give you excessive heartburn, and they almost never, never, never can be fixed at any cost. They were a good tranny back in the day, but the day is long gone. Your choice is between the venerable toploader 4 speed, the T-5 5 speed, or an AOD.
Best,
Al

If you are looking for overdrive and are leery of an AOD, then the T-5 is you choice. It is not quite as strong as the toploader, but it does offer the overdrive. As to expense, you could be looking at anywhere from $1,000.00 to 7,000.00, depending on what you spend on parts (new tranny or rebuilt) and how you set up the clutch (mechanical, cable, hydraulic, 10", 11", etc.).
While the 8" rear gear is fine behind an automatic, it can be really challenged behind an agressively driven standard tranny. If you drive with your hair on fire, you probably need to scrounge up a 9".
Best,
Al