If you're using a R151F that comes stock with the 1KZ-T, 1KZ-TE, or 3.0 liter v6 you'll need Marlin's adapter to fit it to your gear driven Tcase.
If you're using a R151F that came from a 86-87 turbo truck in the US/Canadian market (22R-TE) you'll need to use the Tcase that came with it (as it has a 23 spline input shaft). Otherwise you'll need to convert your G58's gear driven Tcase to a 23 spline input shaft. Marlin has those also.