My 400 turbo tranny started slipping today and..

I was wondering if it is going bad or if i need to rebuild it and put a shift kit in it.?? it goes through first and second ok but I have to shift the shifter into third or it will slip. When i do it manually its ok but when its by itself it slips. I need some websites with nice cheap 400's and or rebuild kits and shift kits.  

is it old? you checked fluid im sure.sounds like rebuild is coming soon.  

Kits are cheap but the main question is can you build it yourself or are you gonna take it to a trans shop?  

i had my th350 built last year for 600  

shift kits sometimes correct problems. they are sometimes called correction kits , shift improver ext. you can also upgrade the valves for higher pressure ones and that will help promote better shifting and lubrication.

i learned alot from this website , they have an extensive amount of parts. they also offer tip sheets for some transmissions.

http://www.400raptor.com/  

Well the fluid is good. but my dad said maybe the modulator is dirty and or the filter. Its in a 69 Chevy CST20 longhorn 3/4 ton truck. I can so the kit myself and not so sure about the shift kit. Im changing both filter and the modulator this weekend so it might fix it.  

Dirty fluid or filter will def cause trouble in an automatic  

Its kinda fraking me out cause I dont have 1200 for a new quality built tranny. Or even money for a complete rebuid so I thought I would come on here and ask some possible problems.  

1200 bucks is way to much for a stock 400 trans. You can buy a good one for less than a grand. It costs bout $350 to get one rebuilt with a convertor where I live. First thing is to change fluid and filter to see if it helps  

350 is a good deal 600 is cheap around here  

It helps to have friends in the transmission biz.p2 what part of the country do you live?  

flint,mi.best tranny and rear end guy in the city did my tranny for 600 and rebuilt my 10-bolt with a 3.73 posi for 900(1500).where do you live?  

Close to athens,ga. I do my own rearend set-ups but I get trans work done so cheap I've never tackled a rebuild myself. If I ever lose my connections I will have to learn to do that to! lol  

ya you cant beat $350.i wouldnt even care if i broke it if thats all it cost me  

Yeah if it only lasted 20,000 miles it would be a deal considering most projects dont see 5,ooo mlies a year