I am doing a similar swap on my 94 sonoma 5.7L, a dana 44 out of a Jeep wagoneer is a great doner. The dana 44 is strong enough to handle whatever your 350 can dish out and tires up to 35". Many parts are also available to make it even stronger. The Jeep dana 44 is also a great width to use under the S10 and the diff is on the drivers side making it match up with the transfer case well. It will have a leaf spring setup and disc brakes. I found mine on an 83 wagoneer, bought the whole truck for $300 and took both axles (AMC 20 rear). I am swapping in both axles so I will have the same width axles/gear ratios/6 bolt lugs all the way around. The front driveshaft was also a double cardigan type (meaning it has a dual U joint on the front) and the front axle already has a steering stabilizer from the factory.