Rebuild trans?

[juicy]

driving home from a buddies house yesterday, and before i get on the free way i hear a clunk, think nothing of it, hop on the freeway, really get it on it, and realize that im 5500 rpms but only going 50, i realize something is wrong, i only have a 1st and 2nd gear, so the question is... rebuild time or what? how much am i looking at spending? and any reputible shops in so cal?

 

truck specs

 

1999 silverado 4x4

6in lift

3in body

4.56 gears

106000 miles

[GM-Tech]

Possibly electrical. Scan it for codes before doing anything else.

[juicy]

Possibly electrical.  Scan it for codes before doing anything else.

 

<{POST_SNAPBACK}>

 

 

 

hrm electrical..

what kind of codes am i looking for? and i really dont want to drive it anywhere, because if it is the trans, i dont want to fry the rear end if the trans goes, what do you suggest i do to get it tested?