yup been there done that ask away..about the same time frame Gator built his I made one from IH Scout II Dana44 axles, a Suzuki Samurai transfer case and 25hp Kohler engine driving a 2-section gear pump..machine runs open center hydraulics,one pump section is for drive and the other pump section is for steering via a power-beyond valve downstream feeding a 3-section valve for loader functions,will lift 1700lbs tested..steer is a 2"x12"cylider on one side of the artic hinge,works fine..drive is made with a Charlynn hyd motor driving a CV shaft directly into the transfer case. The one pic here is a preliminary idea of driving the transfer case with morse chain but it kept stretching with use and was a maintenance headache,so I went to the direct drive thru a shaft and has worked out great since I made that mod.Axles are Dana 44,with 4.11 gears,open differentials,cut down width wise to 48"flange to flange.Im headed out the door on a field job but can get you more pics,ask away..
built this 15yrs ago and it still works great.had some mods along the way, i can tell you anything you want to know..just use full-float axles from a 3/4 or 1T pickup,not semifloats like these.
[Linked Image from kuhnbros.com]
[Linked Image from kuhnbros.com]
[Linked Image from kuhnbros.com]
[Linked Image from kuhnbros.com]
[Linked Image from kuhnbros.com]
[Linked Image from kuhnbros.com]
[Linked Image from kuhnbros.com]
[Linked Image from kuhnbros.com]

The frame is 2x4 3/16 rectangular tubing,some of it is 2x3 rectangular tubing behind the rear axle..the rear axle swings side to side pivoting and the front axle is fixed,welded to the frame..the rear axle has a 1"thick plate cross section welded to it,the machine pivots on a 1-1/4 custom bolt and nut..dont ask where that came from(i know but can't tell) hydraulic drive is super strong and will spin all 4tires under load.I built the machine with a lot of 1"plate,I had access to scrap and used it to build in strength and weight which gives the machine traction and strength like in the articulating hinge and rear sections.
One thing I cna tell you is to DEFINITELY go with a 3-spool valve for your loader so you can have a grapple or clam bucket,it adds so much more usability to the loader,even if you dont use it initially.
Happy to help you design and answer questions,thats what we are here for..best of luck with your build.