I have a problem with a thm700r4 transmission. i rebuilt the tranmission my self because the clutches were burn but now i have a shifting problem with 3rd & 4th gear it doesnt shift past 2nd gear. it starts good n strong in 1st gear then it shift into 2nd gear a little late but real hard then it wont shift into 3rd or 4th gear

Sounds like the clutches for the direct drive drum are shot. Either have it rebuilt or replaced, but make sure whomever installs it knows how to set up the detent cable or it will burn itself up again within a few miles.

You may need the transmission rebuilt, once it starts to slip that is the end in mist cases. Have a local transmission repair shop confirm my guess on this

P0743 - Torque Converter Clutch Circuit Electrical
Possible causes- Faulty torque converter clutch solenoid valve
- Torque converter clutch solenoid valve harness or connectors
- Torque converter clutch solenoid valve circuit is open or shorted
- Low transmission fluid level
- Dirty transmission fluid
Tech notes This is an electrical problem code. Could be a problem to the harness to the TCC solenoid, the TCC solenoid connector or the TCC solenoid it self.
P0755 - Shift Solenoid B Malfunction
Possible causes- Low transmission fluid level
- Dirty transmission fluid
- Faulty shift solenoid B valve
- Shift solenoid B valve harness or connectors
- Shift solenoid B valve circuit is open or shorted Tech notes When the a transmission solenoid is malfunction, in most cases the problem is not the electrical part of the solenoid; the problem is foreign material obstructing the mechanical function of the solenoid or the flow of the fluid through the transmission valve body. If the transmission fluid is very dirty, it is recommend changing the transmission fluid and if possible removing the transmission pan for further diagnosis. Excessive debris or metal particles on the transmission pan could be an indication that there is a transmission mechanical failure and that the transmission will need to be rebuilt or replaced.

Read more: http://engine-codes.com/p0755.html#ixzz27PjeNdA5

sounds like a thrust bearing

Ok if you have 1st and second gear and it shifts to neutral instaed of 3rd , that means the 3-4 clutches are burned up.This is common problem with the 4L60E transmission and the transmissionwill need to be removed and rebuilt ot repaired.The 3-4 clutches are the weak point in the trans and i usually use a z-pack when rebuilding them.It increases hold capacity and durability.

if it has ever been driven low on tranmission fluid this could be a bad sign, check the fluid level, assuming it is and has been full this could mean your internal clutches are worn, and tranmission will have to be rebuilt or replaced, the color and scent of the fluid are good indicators of burnt clutches, if it is more brown than red, and smells burnt...thats bad news

You have worn clutch facings a weak sprag ring retainer springs.Also the direct drum is worn intenally and the sun gear bushings will be fairly worn too. Your truck is ready to get a rebuilt transmission
All issuses as described tell me this has high miles or a hard life on the trans per say as towing or lots of city driving

sounds like your third and forth clutches are burnt up. one set of clutches powers both gears. transmission will most likely need to be overhauled

Here's was the code means:
P1870 Transmission Component Slipping

A code that indicates a problem with your tranmission. Ususally causes a hard shift from 1st to second gear. Need to have a transmission expert look at the vehicle. Most cases the torque converter is the main problem. But, sometimes the transmission may need rebuilt if damage has occurred.

With that Burning Smell it is the Transmission Burning up the Clutches on the Inside. Gonna have to get it Rebuilt.