A servo vs. A+ servo vs. B servo...what is REALLY necessary?

[bcmbcmbcm]

I will be swapping valvebodies at some point and will have easy access to the stock B servo. But my motor is stock.. so do I really need to spend $140 on a billet A+ servo?

Can I put in a factory Ford A servo?

What vehicles came with the A servo (to aid in looking it up?)

and finally, will it really help? I know all the built AODs have them, but for a stock application, will I see any benefit in performance and/or longevity?

Thanks everyone!

 

[RYC CUKR]

Here you go this link will tell you what cars and trucks the A servo came in and it also has some other good info on AOD upgrades

http://www.becontrols.com/tech/aodsupgr.htm