I ask because I have a D150 with a slant 6 and a 727. The /6 guys are all saying that the 727 saps too much power to run vs a 904.
My problem is that I have had many of both a 904seems quite weak, I don't have much luck with them.
Being that I have the 727 already it seems like a bonus to me, many are saying it is really a curse.
I have heard 15% to 25% I have heard "about 100 hp" which can't be because that is about All my stock slant makes. If that were true the truck would not be able to pull itself at any speed above a crawl.

I am going a different direction with this one, previously on past-owned vehicles, I did the typical "yank the slant 6 and put a V8 in its place" but I am experimenting with building up another slant 6 for this one, to see what I can get from it.

Via a google search I came upon a discussion on trans power consumption on a Dodge charger forum of which I am not yet a member.
I did recognize some names in that thread over there that I see here also. John Kunkel among others. Hopefully he sees this question posted here.
While I definitely realize that I will most likely have to overhaul this trans just because of it being 35 years old if nothing else. I know they used ALOT of 904s in half ton trucks as well but I'm not looking at going that direction. If I swap to a different trans it will be something with an OD so being as how I have never seen a 500 or 518 cast with a slant bell housing, it will probably be converted to a manual.
But for now the 727 stays. I may look into some other torque converter to slide in when I put my fresh engine in, and possibly some sort of a shift kit to hopefully improve on (cut down on) the amount of power that the trans robs, but definitely not looking to do anything as crazy as putting 904 guts inside as many racers do, this is a truck, and 90% of the time it will just be a daily driver, but I do occasionally want to pull my pop-up with it or maybe my utility trailer with a garden tractor on it.
Any ideas?

Playing devil's advocate here......with all else being equal how much more zip would I gain and/or mileage (which is not my #1 goal here btw, but had to ask) what would I gain by going to the weaker trans?

How much does converter choice have to with the amount of power lost/consumed by the tranny?