Drivetrain Upgrade Qs - 91 V1500 Sub

[JungleBoy]

Guys
First time in - great to see a Gen 1 forum to go along with this one. For towing, I need more power for my 91 V1500 Sub (350 TBI, 4L60, NP241 and 10 bolts front and rear). I have installed hydroboost and Praise Dyno Brake rotors, pads and shoes and finally have brakes with a capital B.
The plan is to install a 383 with upgraded TBI. What I am thinking about is upgrading the drivetrain as follows:

14 bolt SF 6 lug rear
TH400 with Gear Vendors OD
NP205

I know some of you guys really use your Blazers - any comments or suggestions?
Thanks in advance
JB

 

[HarryH3]

Have you priced that Gear Vendors Overdrive yet? Whew! They're VERY proud of it! Plan on spending about $2,500 for it.

<font color=black>HarryH3 - '75 K5</font color=black>
<A target="_blank" HREF=http://ThunderTruck.ColoradoK5.com>http://ThunderTruck.ColoradoK5.com</A>

 

[JungleBoy]

Yeah, but an old drag racer who runs a trans shop here in Houston told me this is a lot stronger setup than a 4L80E, my first idea...

 

[HarryH3]

I don't know how much, if any, stronger it would be, since the 4L80E is supposedly based on the Turbo 400. For a tow rig though it would be great to have the extra gears you can come up with using the Gear Vendors unit. 2nd gear and overdrive can be just the ticket in the mountains when 2nd is just a little too low and 3rd is just a little too high.

<font color=black>HarryH3 - '75 K5</font color=black>
<A target="_blank" HREF=http://ThunderTruck.ColoradoK5.com>http://ThunderTruck.ColoradoK5.com</A>

 

[fr8train]

Why not check into Jet Performance 4L60, 4L80, 700R4? They will cost you about the same and by the looks of the mill your going to run they wont be getting messed up. That is, unless you fog the mill. Also so on the TH400 note. When it was debated on this site before someone is quoted to have read: "TH400 can suck up to 60HP from a mill". Do some searching on the TH400 and you'll find it. The general concensous here is that the 700R4 is crappy. Well, its stock, what can you do? One of my best friends and fourwheeling buddies runs a jet 700r4 behind a built 400sb. It goes thru a 205 to Dana 60s. He hasnt broken it yet and the only thing to fail on it is the old carb setup.

 

[JungleBoy]

I know some guys drag race 700R4s, I was surprised by the old man's statement that GM ODs are frail (this discussion occurred when I was talking to him about rebuilding my schoolteacher wife's 4L60E in her mall runner '97 K1500 Tahoe with 50k miles). He also told me that no one makes aftermarket bulletproof planetaries for these ODs, including the 4L80E. I calculate the cost of a 4L80E about 3 large with computer.
Didn't know, though, about the degree of parasitic power loss with the TH400. How does this compare to the 4L60s or 4L80s?
Thanks
JB