If the car only has 78k on it and has been well maintained to this point I'd imagine that you don't need a high mileage fluid. It won't hurt if you wish to use that though.
Are you having any seal issues, shudders, rough shifts, etc..?
Assuming all is well and you're looking for a superior product off the shelf the Mobil 1 ATF has given great results for many here. Amsoil is another product many recommend. I myself use conventional Pennzoil ATF in a 95 Aerostar with nearly 200k on it. I also use their gear oil in the rear diff. Matter of fact I now use their conventional everything in both my vehicles. It's just simpler for me, not a testimony to Pennzoil though I have good results from their products.
On the main forum page is a link to all the site sponsors for Amsoil, Shaeffer's, Specialty Formulations, etc.. These are more boutique lubricant producers/designers but all offer extremely good products as well.
As far as gear oil in the diff for your car I really am not qualified to say. I'm sure a gear oil will be fine but I've no idea what specs you'd need to go with
Hopefully, one of the many more imformed members of this board can chime in!
