727 to 47rh swap
 

I've been tossing around the Idea of swapping the stock 727 to a built 47rh. What all would I need to do to get it done? New bell housing, starter, flywheel, moving the cross member, driveshafts (2wd), and running switches. Or would it just be cheaper to build up my 727 to withstand a good amount of HP

You pretty much have the main part of the list listed. I have a kit we make with all the components to let it go into OD then LU automatically without having to throw switches. That 0.67 OD makes a HUGE difference. If you dont mind the RPM build the 727 otherwise add some clutches and a valve body kit along with a 1200-1400 stall to the 47RH and get to work. There are some 47's out there without lock up, be sure to get the one with the 3 wire switch next to the linkage shaft.

I found a 46rh with only 70,000 miles which I'd rebuild anyways to make sure it's sound. The truck is primarily used for dump runs and hauling hay. What am I looking at cost wise for a 727 rebuild compared to a 46rh rebuild and swap?

The cost of either rebuild are negotiable at best. The 47RH is gong to be a bit more due to converter difference but beside that its not much different other then over drive clutch parts. The swap is more due to mentioned parts but is better in the long run due to MPG savings.

Doubtful I would rebuild a 727 if I had a 46rh. But without the lockup, its not a hauling gear.

You may want to factor in an axle ratio change (3.54/3.73). More grunt on the bottom end, and be able to use OD at less than warp speed.

Be sure you get the 47RH as the 46 is a gas bellhousing pattern. Lockup is a plus but not having it should not be a deal breaker if the price is right but, try to get a lockup unit if you can.

a518 and 46rh terms are often used interchangeably. The gas one won't fit the diesel.

The 47rh needs the thicker 2ndgen adapter plate also, and the matching starter.

NO, the A518 and 46RH are GAS only!!!! There are no A518/46RH diesel transmissions!!!!! So you want to be sure you use the right terminology when you buy this transmission for the diesel which needs to be the 47RH. Use the right verbiage so you get what you mean and are looking for. The second gens are NOT thicker, where does this stuff come from... If you have a 1st gen lock up is uses the same adapter as the 2nd which has lock up. Its been a long time since I did a NON lock up diesel unit but it might have a thinner adapter then the lock up but I am not so sure it is, as it has been about a decade since I did a non lock up swap. Heck that was the last time I had one of those converters in the lathe as well. I dont remember if the non lock up has a thinner converter and adapter or not, if it does maybe thats what you mean by the thinner statement. I know the Gas lock up or non lock up have the same depth converter but, I dont remember on the diesel.
Anyway, be sure you use the 47RH statement and NOT the 46RH statement while buying a transmission. If you said 46RH at my shop I would sell you a 46RH if you came in asking for one. Do note that if you talked enough about your truck or swap I would figure out you needed a 47RH and not what you asked for but, only if you talked enough about it.

The 47RH is lockup only. The a518 is a diesel trans. Whether its correct or not, many call them a non-lockup 46rh. BD Power makes and sells parts for the diesel a518.
https://www.dieselperformance.com/sh...smission-44442

I haven't encountered a lockup trans in a 1stgen diesel. I have 2 extra adapter plates from these trucks, and they're about 1.5" thick. I have one 'thick' adapter plate (~2.5") I personally took out of a 95 Dodge diesel.

Does the 2.5" adapter use a Dodge transmission or a GM? Also, what are the thinner ones bolted to? We just rebuilt a 1992 with a Lock up. Do you have PICS???? I love to document this stuff in my achieves I keep.