Need some questions answered - new build

[FlyingT]

I posted in an earlier thread about attempting to build a mountain buggy. Had some great advice regarding type of cart to use as the platform, torque etc..
Here are a few more questions that I'm hoping for some expert opinions/advice.
1. Decided to go with an aluminum frame CC as the platform. Is there a date range of Series carts I should avoid? Currently looking at a 94 36v and a 99 48v. Recommendations? AC vs DC motor?
2. Thoughts on the rear differentials for both...how to make limited slip?
3. What brand of engine with high torque/low speed (8-15mph) do you like w controller.
4. What's a good 4x4 Kit to use or should I just go with 4x2. Grade we are climbing is less than 20%.

Plan is to transport 4 guys up the mountain about 1.5 miles and park it twice a day. Need to be efficient so I'm thinking of going with Lithium at some point to save on weight and not have the battery maintenance etc.. We are in a colder climate and have an off-grid cabin powered by a propane generator that we fire up for 4-5 hours each day while there.
That's a bunch to ask and I appreciate any and all feedback. Thank you!

[jakesnake27]

1.) Are you going to drop in an entire new electric drive system? If so, it really doesn't matter what year you get, as the frames were the same. Just make sure the frame is in good condition and not corroded badly.

2.) Guys have done it on here, I think you have to crack it open and weld the gears. I just don't have experience doing it.

3.) Plumquick makes some great motors. I would contact them with your needs, they are a site sponsor here.

4.) You will probably be ok with 2X4, but there is a sponsor (Silverwolf?) that sells a 4X4 kit.