Although Craigslist ad stated $1200.00 FIRM. $1000.00 cash completes the transaction.
We agree to meet in a very public place, I am driving 80 miles, the seller 50 miles. (For your personal safety, always select a very busy public place to conduct Craigslist business, NEVER conduct Craigslist business at your residence.)
Very nice gentleman, states he purchased the Gear Vendors unit as a spare and it was previously used for about 50K miles in a Chevy Suburban with a TH 400 tranny. The cosmetic condition indicates that is likely a true statement.
Looking good so far.


The Gear Vendors electronic control box is intended to "idiot proof" the functioning of the overdrive by automatically prohibiting engagement below 20 MPH since the internal hydraulic pump doesn't build sufficient pressure below 20 MPH to tightly engage the cone clutch.
Since the primary goal is to reduce highway RPM's, a simple on-off switch and indicator light is a personal preference.
The need to split between gears isn't anticipated at this time, however if required, splitting is possible manually with attention to not having the unit engaged below 20 MPH.
Sold the electronic boxes, foot switch and wiring harness within 4 hours after listing on eBay for $150.00.

Two adapters and a splined coupler sleeve came with the unit.
Researching casting identification marks one adapter is marked "350S" and on the other "241". It was determined these parts had been behind a NP241 transfer case, not the GM TH 400 as stated in the Craigslist ad.
Possibly quite fortuitous they would be bolting up to a NP241HD.
The 32 splines in the coupler fits a 1.378" output shaft indicating if it did come from a GM vehicle it was heavy duty. We'll know soon if it installs properly.


The 1350 series output yolk as received was fixed to the Gear Vendors output shaft with a bolt and a heavy washer. This same yolk could be used as a slip yolk by sealing the yolk's center hole with an appropriate plug.
The Dodge Cummins (and V-10) driveshafts are equipped with 1410 series fittings, so the 1350 series rear yolk has been listed for sale on eBay.
Gear Vendors evidently gets the slip yolks supplied without identifying markings so most think they can only be purchased from Gear Vendors (at inflated prices).
The specs below can be used to obtain a 1350 series slip yoke from other sources.

The specs for a 1410 series output yoke is shown below, however there is no outside source for the proper barrel length in the 1410 series yolks.
The NP241HD transfer case output slip yolk on the driveshaft is of the exact same specs, EXCEPT for the length.
A slip yolk was obtained from the wrecking yard and was cut on a chop saw to the appropriate length. Care was taken to cut slowly and wipe with a wet rag so not to overheat the barrel and lose the heat treating. A beveled relief on the the end of the barrel and on the inside spline area was carefully ground with an angle grinder, again carefully keeping heat to a minimum.