Well I installed a rebuilt 4L60E in my 2000 Silverado 4x4 that I bought from this guy who rebuilds them,well first it wouldn't shift from first to second to I dropped the pan and changed the wiring harness, and still not shifting,I've tried everything I can think of,so today for the third time I pulled the pan and this time I changed all the solenoids,I cleaned up my old ones from my tranny I pulled out an put them in this tranny,so. I test drove it, so this time it did shift but I had to let off the gas pedal and then it felt like Third gear

 

Have you scanned for codes?
What year is the rebuilt 4L60E?

 

No codes and was rebuilt this month

 

I meant what year model is the trans? E.g. from a 1998 or 2009 vehicle?
I wonder why you say "changed the wiring harness" - did you just replace an old one or install one for a different year that what the trans originally had.

I'm grasping for straws here but since no obvious problem/solution jumps out for me, nor evidently anyone else, I want to start with basics on the assumption the trans was rebuilt correctly and you only have an electrical or compatibility problem.

 

Well the transmission is a 2004 but I replaced the wiring harness with a new one because the one that was in it had two broken clips,and yes I hope this thing was rebuilt the correct way,but after changing all the electrical in the tranny and checking to make sure no springs were broken in the valve body and all the plungers are in there and none stuck,I have everything except second gear,all the others work great,shift good no slipping, just no second gear

 

Your 2nd post is much more informative than the first; from the first I though the trans was either stuck in 1st gear or perhaps in Limp mode.
If only 2nd gear is unavailable, this is most likely a servo problem. First check the servo end play by pressing on the servo cover with e.g. a crowbar and estimating how much it moves in. Spec is 1/16 to 1/8 inch. Around 1/4" you lose 2nd and/or 4th gear. A newly rebuilt trans should have a new band and therefore be in spec.
A broken servo piston, broken seal or worn body could cause loss of 2nd gear. Sonnax makes a set of o-ring seals that work better with a worn body.
Servo/band problems affect both 2nd and 4th gear, but symptoms often start with either gear and not both.

 

Well I took the servo out of my old tranny and stuck it in the new tranny so now I have first gear,second gear, fourth gear,overdrive,but now I don't have third gear,this is getting on my last nerve

 

If reasonably easy to do, try disconnecting the harness connector to the trans.
This should force 3rd gear. Does this give you 3rd gear?
Confirm that you had 3rd gear with the 1st servo?

It is very strange that you have 4th gear but not 3rd; not sure I have ever heard of that.
Perhaps if the band is not releasing.

 

Where the plug is located is very tight to get to but I will check it but the 2-4 servo I changed,the pin in the servo I took out and the pin in the one put ,they both had two groves in the tip of the pin so they we both the same length,see when it started there was no second gear,I was on my way home,about 75 miles from home but when I would start off it would be in first,I would get up to 20 mph and let off the gas and when the RPM's came down then it would go Into third and shift fourth and OD but the next day I drove it and it was working the same and I noticed the RPM's going up and my speed dropping so I came back home,that is when fourth was gone,so I pulled the servo and the bottom o-ring was broken so I put the servo out of another transmission in it,when I started off in second,It was in second,then started off in drive and it shifted from first to second then tried to go into third but then started slipping so I stopped and started off again but when it was ready to go into third I let off the gas and it went into fourth and when I made it downshift it went into like nutiral or third but no gear there,I changed the shift points 3 mph sooner with a programmer but didn't help