Jeep NP231 for a 4.0L with a 23 spline input. It is built with a the TeraFlex NP231 4.0:1 Low Range Gearing Conversion kit and Tera Extreme Short Tail Shaft Kit.
$1200 obo located in Colorado Springs
This is a straight bolt up for all 87-04 Jeep Wrangler YJ & TJ with 6 CYL and AX15 or NV3550 Manual Transmissions.
For more info check out quadratec: 4:1 Kit
& Extra Short SYE
The Tera Low Conversion Kit is the best solution for providing CJs & Wranglers with low crawl ratios. This kit increases rock-crawling performance without affecting the high range for the trip to and from the back country. It provides true 4.0:1 reduction without the noise of older planetary systems. Every part in this kit is new; there are no core charges. Shift linkage and driveshaft length changes are not necessary. The Tera Low231s high input torque rating suits it for use with V8 engines.
Etreme Short Shaft SYE
The ExtremeSS kit increases stock driveshaft length by over 7", a valuable gain for short wheelbase vehicles. The ExtremeSS kit comes w/ all necessary components & hardware to modify the stock 231 case. Speedometer readings are transferred through a tone ring & electronic sensor that can be custom calibrated by an aftermarket calibration converter box to match custom ring & pinion/tire size modifications.