In 1992, General Motors and Dodge began equipping their trucks with a new heavy-duty, 5-speed manual transmission known as the New Venture 4500, or simply NV4500.  This is a 5-speed, constant mesh transmission with all forward gears fully synchronized (Dodge models even offer a synchronized reverse gear, and that can be added to the GM versions).  It is a large and extremely sturdy transmission constructed with a cast iron case and aluminum alloy top. It weighs in at just under 200 lbs (dry) and was designed with the strength necessary for one-ton truck applications with a GVW rating of 14,500 lbs.  The 5th gear is an overdrive with a gear ratio of 0.73:1.   Immediately upon its introduction, this transmission was recognized by off-road enthusiasts to be an ideal transmission for conversions.  In addition to its strength and overdrive gear, it offered an ultra-low first gear ratio of 6.34.  Unfortunately, the ultra-low 1st  gear was discontinued in 1995 and replaced with a higher, but still-impressive 1st gear ratio of 5.61.  To put these gear ratios in perspective the stock TLC 4-speed has a 1st  gear ratio of 4.9:1. The early, low-gear-ratio transmissions are obviously in high demand and with low supply (need I say expensive).

In weighing the options, availability and cost, we chose to purchase a 1995 model from a salvage yard.  It came from a 3/4 ton Chevy 4WD that was rolled and totaled with slightly more than 15k miles on the odometer.  It has the following gear ratios:
First Gear
Second Gear
Third Gear
Fourth Gear
Fifth Gear

We compensated for the higher-geared NV4500 by trading our '78, 4-speed, H42 transfer case for a 3-speed, J30 transfer case.  Our J30 is a '73 model, completely rebuilt by John Groves of Cruiser Parts in Grants Pass, OR. Advantages of the J30 transfer case, relative to the stock '78 (H42), include a low-gear ratio of 2.313 (relative to 1.959) and an arguably stronger case.  As shown in the following table, our combination of '95 NV4500 and J30 Transfer case results in a final gear ratio lower than that of the earlier-model NV mated to a stock '78 TC.  Our final ratio does not approach that of a Marlin Crawler, but is a significant improvement over stock. The following table gives some comparative final 4WD, low-range, gear ratios, including what we might achieve by a future upgrade to 4.88 R&P gears.
'78 FJ40
Stock TC
4.11 R&P 
NV 6.34
Stock TC
4.11 R&P 
NV 5.61
Stock TC
4.11 R&P 
NV 5.61 
J30 TC
4.11 R&P 
NV 5.61 with
J30 TC 
4.88 R&P 
Final Gear

All adapters required to mate the NV4500 to the Vortec engine and the TLC transfer case were purchased from Advanced Adapters Inc.  Vic Carrol at AA was especially helpful in selecting the best components and in answering questions following the purchase.The required parts for this conversion include the following:

The NV4500 transmission requires modification before it can be mated to the AA adapter assembly.  Most, if not all, GM 4WD transmissions obtained from a salvage yard will include the GM TC adapter housing, 8.125" in length.  Removal of this housing reveals the NV output shaft, overdrive gears and a large (5"dia., 4" long) harmonic balancer.  This balancer must be removed.  The recommended procedure is to purchase a GM SST socket to remove the retaining nut.  After learning of Mr. Goodwrench's price for this special socket, I made one myself.  Unfortunately, even with my very heavy-duty socket and an enormous air impact wrench, I could not budge the retaining nut.  After hours of work wasted in building the SST, I ended up taking 15 minutes and drilled two 1/4" diameter holes on opposing sides of the nut and broke it with a chisel.  This is definitely the easiest way to remove this balancer.  The photo to the left shows the NV4500 with the balancer removed.  The threads between the two splined sections of the output shaft are the ones threaded for the balancer-retaining nut.

The AA approach to mating the NV4500 to the TLC transfer case is accomplished with a spud shaft that slips over the NV output shaft, extends through the adapter housing and into the TC, becoming the input shaft for that gear box.  The NV4500 is a very long transmission, and in order to reduce the total length of the complete assembly, the AA conversion requires that the NV output shaft be cut off just aft of the foremost splines.  For this procedure, I used the steady hand of my understanding wife to slowly turn the shaft while I cut with an air-powered cut-off disk.  This photo shows the shaft after being cut at the AA-recommended length of 4.5" from the rear of the transmission housing.  AA also provides the set collar shown, secured to the shaft with two allen bolts, to hold the overdrive gears in proper position.  The AA spud shaft mates with the splines on the rear of the shaft in this photo.  The gears and shaft illustrated in this photo are lubricated by the main NV4500 synthetic oil bath. The NV requires use of special GM or MOPAR synthetic gear lube, and consequently an anerobic sealer must be used in mating and sealing all components in contact with the lubricant.

The photo above shows the entire drivetrain, including the VORTEC engine, bellhousing, NV4500 transmission, AA adapter housing and transfer case.  The entire gear assembly is 34.81" long, including bellhousing (5.312"), transmission (12.375"), adapter (5.875") and TC(10.25"). Note that the shift lever of the NV is set toward the rear of the box.  This and the long length of the NV allows the VORTEC to be placed as far forward as possible and retain the shifter in approximately the stock location.  We ended up moving the opening for the shifter in the transmission cowl/tunnel less than an inch to the rear.  By placing the entire drive train as far forward as possible, we were also able to end up with a slightly longer rear driveshaft, the extra length resulting primarily from the spring-over conversion.

The above photo shows the bellhousing, NV4500, AA adapter and transfer case in their final position in the Cruiser.  The NV shift tower sits well behind the heater and with its short throw is ideally located for optimal shifting.  Note, however, that the AA transfer-case shift bracket results in the stock TC arm located about 2.5" aft of the NV shifter (and cowl hole).  To overcome this mismatch, avoid elongating the TC hole in the cowl, and provide a longer TC shift lever, we fabricated a new and longer shift lever that includes a bent extension moving the lever forward.

Breather ports for the NV and transfer case have been plumbed into a 0.5" rubber line running to the top of the engine bay where they mate with similar lines from the two differential housings in a KNC breather filter assembly.

Finally, the photo below shows a view of the rear view of the NV assembly.

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