94 transmission question

I have a 94 suburban v8 5.7 2wd 1500 with a 9" lift and 37 inch tires has 200000 it had the transmission replaced 3000 miles ago well I was driving the other day and it reved hard and didnt shift so when i got home less than 1 mile away tranny fluid was pouring all out i checked the level of fluid and was almost out so I started looking for the leak which i found on a silver line (there are 2 of these they come from the radiator to the back of the transmission) **sorry I am a girl dont know all the names of all the parts** so I got some j b weld and patched it up still has a small leak so i filled it full of fluid and test drove it up the road well it shifts fine from 1st to 2nd but after you reach 35 miles per hour at reves up and wont shift. WHY is it doing this??? the check engine light will come on now after about 3 mins of driving it then go out I am planning on just replacing this line ($29.99) but if it wont help the tranny shift I need to know what the problem is I still can drive in reverse and there is no noise coming from it it still runs quiet any help would be much needed as I am broke and what to try and fix it on my own

ok I have narrowed it down to 2 things one the filter being clogged from running it low on fluid or 2 burning up the gear.......how far would you have to drive before a gear burns up like I stated before i drove it a mile after the first enitial hard rev up and kept it under 35 mph

First fix your leak with a new line. Then fill the trans. with fluid to the full mark with the engine running. Then take it for another ride.

ok i went to the part store 8 am after pulling out the filter at 7 am put it all back together new fluid and all still not engaging in to gear after 35 miles per hour :banghead: and if i buy a new line instead of fixing the old one the new ones is one big long straight line i have to bend into shape any ideas on where to go from here

JB Weld is some good stuff, but! It doesn't replace a good solid line. You really didn't say were the leak was. If it was at or near the tranny maybe with only 3,000 miles since being replaced the whole thing might be covered under a warranty from the tranny shop. Bottom line (sorry to say) is you probably fried it. No matter what, the line needs to be replaced. Pull the old one out and use it as a model for the new one. Tubing bending tools are not that expensive, just make sure you get the right one for the size of the tubing you're working on.

From the sound of it, the 3/4 clutches are burned due to the low fluid condition. Rebuild time.

//2000CAYukon