3 on the tree

[trucknorris78]

This is mostly to see what opinions are out there. I am doing a frame up resto on a 78 GMC c15. I already have a 427 pushing 555hp. I want to keep the 3 on the tree because, I'm weird, I guess. Dearborn, M13 seems to be the only valid option. I do not yet know what rear gears I am going to run yet but, I am going to fab a 4-link rear. I am not racing the truck but, I am definitely going to play.
I'm going to pay for asking this but, what do you all think?

 

[SquareRoot]

This is mostly to see what opinions are out there. I am doing a frame up resto on a 78 GMC c15. I already have a 427 pushing 555hp. I want to keep the 3 on the tree because, I'm weird, I guess. Dearborn, M13 seems to be the only valid option. I do not yet know what rear gears I am going to run yet but, I am going to fab a 4-link rear. I am not racing the truck but, I am definitely going to play.
I'm going to pay for asking this but, what do you all think?

 

[squaredeal91]

I like 3 on the tree myself too. Fun to speed shift lol, my 61 had the tree and I miss it.
I worked at the local lumber yard a few years ago and did the maintenance on there fleet of old hyster lifts,continental flathead engines. Anyways They were 3 on the tree also and lots of fun!
With that amount of horse it probably won't last unless you can build the transmission and or keep your foot out it's going to break. I would definitely like to drive it lol

 

[Keith Seymore]

This is mostly to see what opinions are out there. I am doing a frame up resto on a 78 GMC c15. I already have a 427 pushing 555hp. I want to keep the 3 on the tree because, I'm weird, I guess. Dearborn, M13 seems to be the only valid option. I do not yet know what rear gears I am going to run yet but, I am going to fab a 4-link rear. I am not racing the truck but, I am definitely going to play.
I'm going to pay for asking this but, what do you all think?

I can't judge you for wanting a three on the tree, or help with your selection of trans.

I will add this, though: back in the early 60's, before four speed shifters were robust and plentiful, the racers would go with a steep steep rear gear with a three on the tree. That would allow them to start out in second gear and slam the shifter straight down into third, making just the one shift during the quarter mile pass.

K

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[TotalyHucked]

I can tell you, the guy that bought my old '70 C10 (6cyl 3 OTT truck) put a hot 355 small block in it and kept the 3OTT. It's probably in the ~425hp 400tq range and he's busted the 3OTT several times over the past 5 years. Enough that he plans to put a Tremec TKO behind it. He, like you, enjoyed the odd/uniqueness of the 3OTT but it has finally become not fun anymore.

My advice, go ahead and get a real trans that can stand up to that engine. Cuz the 3OTT flat will not last.

 

[trucknorris78]

I am under the impression that it was never going to last. I must admit, I do not know what a 30TT is. If it is like the one that came in the truck, I already resigned to get rid of it for the Muncie HD (M13). However, I get mixed responses as to the likelihood of that one standing up as well.

 

[DoubleDingo]

3OTT= THREE ON THE TREE

 

[DoubleDingo]

Slap in an SM420 or SM465. Yeah, not as sporty as a 3 speed, but plenty strong and you get an extra gear for the times when you need to work the truck as it was intended.

 

[85K304SPD]

3 on the tree is different, especially with a high HP big block. We used to use 3 speeds in our dirt track cars, but we didnt shift. Started out in high gear and stayed there. They held up pretty good for a while, probably only maybe 400 HP max.
If you are building a hot rod street truck, put an overdrive automatic in it and have fun with it.

 

[TotalyHucked]

I am under the impression that it was never going to last. I must admit, I do not know what a 30TT is. If it is like the one that came in the truck, I already resigned to get rid of it for the Muncie HD (M13). However, I get mixed responses as to the likelihood of that one standing up as well.

3OTT = 3 on the tree. I don't know anything about the M13, whether it's on the tree or the floor or anything. But the guy I'm talking about did all of the upgrades that they sell to that 3 speed and it's blown up every time. He'll get maybe 6-10mo out of it before it's hurt again.

I get the uniqueness of having it, but breaking it and having to pull it out for a rebuild all the time sure would kill the fun for me. I like wrenching, but driving is WAYYY more fun. I have a T56 in mine and that's wayyyyy more fun to drive than a clunky 3-speed. Plus having overdrive is nice for longer runs

 

[Old Guy Bill]

Why??
Now if it was back to completely original restoration, of course.. but you’ve already changed the engine… so do the transmission also.
We also used a truck three speed in oval track cars, just using high gear.

 

[Ricko1966]

So it's not a frame up restoration.

 

[Rickf]

I'm on a pre 1960 "oldgmctrucks" website. One of the members MacGyvered up a 4 on the tree with reverse a separate lever thru the floor. For the most part we run inline 6's with low HP and torque.

 

[squaredeal91]

I'm on a pre 1960 "oldgmctrucks" website. One of the members MacGyvered up a 4 on the tree with reverse a separate lever thru the floor. For the most part we run inline 6's with low HP and torque.

That's a great idea! I'm planning to do a similar thing by using a 3 speed floor shifter on my side loading 4spd and having reverse sepererate.

 

[trucknorris78]

Great info / suggestions. I am currently looking at the T56 or TKO / TKX. I am not building just to break. Now I am down another rabbit hole. I can find used T56 out of corvettes but, that comes with a whole different set of issues. Anyway, I'll get there. Thanks again!