I'll be in the market for a build tranny in the next few months, something that can hold like 500hp/1000TQ. I was thinking...the 47rh is just a 727 with an O/D unit, and my O/D has never worked anyway. Could I just swap in a built727?

 

Rather than going thru a swap, why not just get it built right???
Many of us are running around with those numbers.

 

Agreed, that would be taking 2 steps back, no overdrive and no lockup. And I'm not mentioning the other improvements that are made to the 47RH when compared to the 727 and 518's.
The extra costs involved with the swap, like drive shaft modifications, trans mount, t-case linkage, etc... could be put towards building the 47RH correctly.

 

Without O/D and T/C lock, you are not going to be happy in my opinion. I cannot load my engine well until I get into O/D with the T/C locked.
Also, without a locking T/C, you are going to make a fantastic amount of trans heat if you tow much of anything.