I have the A518 aka 46rh that is 2wd in my 4wd truck. Now im in the process of getting 4wd back and all I needed was the 4wd overdrive unit. Well I now have the 4wd overdrive unit. I was wondering how hard is it to swap out the Overdrive unit from the 2wd and put on the 4wd. All the spline counts match up, transfercase matches the tranny matches. What kind of work would I be looking at? I know you need the spline tool to match it up. Would it be worth just taking to a shop? When I bought it found a few metal shaving in it, little tiny grit nothing large. And I also noticed these 2 lines cut (picture below) which explains the metal little grits. Truck ran fine with the overdrive in the truck even got to witness it. I doubt I will ever use the overdrive on theses 42 inch tires other than on the highway and if that. Gets up to 70mph no problem with no overdrive and I really dont use the highway.

 

Is there anyway to flush out the overdrive unit? I would hate to destroy my tranny cause the overdrive unit has crap in it.

 

Does the O/D unit actually unbolt from the 2wd trans?

 

Yes

 

Well, that helps.

I suspect the only way you are really going to be able to clean out the O/D unit, is to disassemble it, I suspect you will need to tear it down to replace those lines in any event, otherwise, I can pretty much guarantee you will have issues.

 

Overdrive unit was good, those lines are suppose to be there cause there the oil feed lines apparently. Have you ever removed one of these O/D's before? DO I have to get a speical gear to line the splines back up? Do I have to mess with the parking prawl?

 

AFAIK the only differences in the 46RE(2wd A518) and 46RH(4wd A518) is the VB, servo pots for the front/rear bands, and pan shape/depth, and of course presence(or lack of) inner oil lines for 4wd). The only one that would really be important on a graph like what you seem to be doing is the VB and inner lines. I know that with the "married transfer case" you would need a shorter rear driveshaft in addition.

The only reasons to mess with the parking pawl hub is if it is noticeably chewed up ( people slamming them in park while still rolling)
The only reason to mess with that 800lb Spring, and the output shaft clutches it if the are suspect for bad wear and slipping or known issue and replacement.

As for the pawl itself inside the tail house case it goes without saying, unless you look into the tailhouse and it appears damaged or badly worn don't bother it.

It is often recommended to use a "special tool" to alighnt the OD clutch plate splines when you have opened the tail house and removed the OD/Output shaft clutch assembly...with some caution and upper body strength endurance you can wiggle and twist them all aligned as you drop the shaft through them.

Thing is if you really pay attention to the "tools" you see used or even sometimes sold, they are nothing more or less than a bad shaft with good splines someone has lopped off into a more user friendly lenght.

As for reattaching the the tailhouse to the main case---don't spare on assembly lube, be liberal with the grease or you will fight it every inch of getting the shaft to drop into the splines.