Can’t get the front diff to fit In!

Tell us exactly what you bought, and what you're having difficulty with.

As far as I know Suzuki doesn't sell the front differential as a complete assembly, only as the component parts, and perhaps complicating matters, some people use the term differential to refer to different things, ranging from the actual differential, (the carrier with the differential side gears & pinions inside, to which the ring gear will have to be bolted), the third member (which has the diff carrier with the ring gear & the pinion, to the complete axle assembly.

Installation of the third member into the empty housing should be the reverse of removal, unless you're trying to install the wrong part, so what is it that won't go in?

In the first few years of gen3 Jimnys the front axle casings changed and the diffs went from an 8 bolt crown wheel to a 10 bolt which is physically slightly larger. Ratios aside, all diffs are interchangeable however if you are fitting a 10 bolt diff to an 8 bolt axle then you will need to grind away part of the opening to allow the bigger crownwheel to fit.