Engine Revs high before going into gear and it seems to shift early

[ackland3]

Okay so I have a 1985 chevy k10 4x4 with the 305.

It has always shifted a bit different but now it is getting worse as i drive it. Now it seems to shift almost as soon as i hit the gas and then once it does the engine revs before shifting from 3 to 4. Not sure on how old the fluid is but i'm hesitant to drain it because of the possible old wives tale of it causing a dead tranny. I recently rebuild the rear end in it and did the suspension but i have also been having issues of it trying to stay running after the key is off. Any ideas?

[78BIG-TEN]

I'm assuming its a 700 because you mention 3-4.All kinds of possibilities here.Disconnected or broken tv cable,stuck tv valve,stuck governor,etc.If tv cable is ok,I would drop the pan and check for  filter blockage,stuck tv,debris in pan.Bottom line is if tranny is dead ,its dead.Others may want to chime in here

[ackland3]

It is a 700r4 I believe. My cousin has heard of a th450 for only 250 and he's a certified mechanic he says it's good would that be a good swap?

[NCali]

That would be a bad swap. The 700 r4  is a good transmission once it has had a few upgrades done to it , but as said above, the throttle valve will cause the trouble you are having. Take it to a trans shop and have it adjusted. It wont cost much , its an easy adjustment for someone that knows how to do it. you will burn that trans up if it is not adjusted correctly.

If you put a turbo 400 in it you will have drive line length issues , cross member wont fit . trans mount in the wrong spot

[ackland3]

She died before getting it adjusted lost 2nd gear on the way home..... Now I have a couple other questions on the top of the carb there is a plug in. What is this for? also my thermostat housing has 2 plugs on it as well one used to have some wiring to it but it broke off still runs and thermostat still works so what is that for?