ya, i talk he said it got rebuild and he had it rebuild for HD, he said something bout the gears, if you picked up speed really fast it will shift out of first gear kinda jerking you, and my speed is right on my truck, i was driving down the road and they have a speed detector reading you speed and had a sign showing you

 

but my truck seems to shift fine any gears after 1st

 

What city in MI? Looks like your finding the right websites.

And as little fuel in tank when you remove it as possible.

Well, actually GM makes a better version of 60e called 65E & 4L70E.

Also, by larger gears. Better to say higher numerically, like going from a 3.08 to 3.73, etc.

 

I agree and probably shouldn't have put it in those words. There are a LOT of shops that can't build a decent transmission and will not hold up with what you want to do.

What RPM do you run at what speeds and what size tires do you have? We can tell you what gears you likely have.
However if they did the gears the would have done front and back. I'm guessing all he's talking about on gears is the shifting

 

idk am not around my truck right now, am in florida lol, and fastnblue i live in buchanan wich is close to southbend or niles, and my dad, wich he knows for sure, he said he had gears put wich are heavy duty, he did pulling with the truck like horse tailers and stuff, but i think when it shifts out of first gears its about over 2k rpm mybe close to 3k if your picking up speed normal

 

Ok, well that helps then. You have a 4L60e which is the smaller and lighter of the two transmissions your generation truck came with. It is a good transmission but has very real limits when it come to handling excess power. I've burned up 3 of them before finally moving on to the 80e. There are people out there who have been able to do alot with a 60e so don't be discouraged if you choose on keeping it!!
The 80e is a longer and heavier transmission that does away with the weak links of the 60e. A couple of the drawbacks of the 80e transmission are that 1st gear is really tall and in order to make it fit in a truck that orginially came with a 60e you have to build/buy a new crossmember. Other than that they are bullet proof (within reason).
I've put 1000hp through mine and it performed flawlessly, I do have an Finish Line transmission though (i.e. custom and $$).
Your shifting problems can be easily corrected by getting it tuned which I highly doubt the shop that fixed your dad's transmission ever did.

 

Let me stop you right there man. You keep saying "Heavy Duty" but that means nothing to us. I've seen people say they got a Heavy Duty torque converter after buying it from TCI. Heavy Duty means NOTHING.

Find out what brand of gears he got rather than just saying "Heavy Duty." The strongest/best gears(in my opinion of course) they make for a 10 bolt are the stock gears. It's a solid piece of steel so it's not going to get much better than from the factory.

 

How true!!!

If you want to learn about trucks and motors and everything in between this is the best place to start, but it will consume your life!!

 

lol my bad, all my dad said is that last transmission that was in it got gutted and had the gears rebuild for pulling, from what my dad said he had it rebuild, and when it got rebuild it got rebuild as a HD transmission randomhero, but i could be wrong, but ill find more out, but i could be wrong on the rpm on my truck, ill take a look at it and record it for you guys and put it on youtube, its been a while since i drove my truck between wreckign then getting fixed, and right after it got fixed i went to florida, and i been in florida for a while, ill be back in michigan sat.

 

if this help, i figured this out when i was passing some one, if i floor my truck around 26-30mph it propaly has the strongest kick when you floor it, it really jerks you hard