I am installing a 402 with a th400 into a 66 elky. but the cross member for the trans mount is way off. I was told the th350 and the th400 used the same cross member. Is this correct?

No, generally I've found the 400 crossmember is a little different. At least it was when I had to change it in my 74. I also had to mount it about 6 inches further back to account for the extra length of the extension housing. HAd to get the driveline shortened and rebalanced too.

One more thing. You may have to change your Emergency brake lines to account for the tranny change. I know I had an issue with the E-brake lines and didn't find out till later that there was a different routing and set of lines when a T-400 was used. I made the old ones work by rerouting them but IT's not really the right way to do it.

That is just about what I am experiencing too. Thanks for confirming it.

I know this is an old thread but its making sense for my elky too.

I've got a 74 with a factory sb400 which as far as I know should have had a th400 stock.

Its now got a th350 in its place. It shifts fine but my reverse lights dont work and my brake light is on constantly.

Would I be better off swapping back to a th400 and finding a correct driveshaft?

?????? What's the tranny got to do with the brake light :? The backup light's controlled by the shift linkage not the tranny itself, isn't it? :dontgetit:

sorry i meant the interior brake light on the dash. fluid level is fine and the ebrake releases but the light stays on.

Check the switch on the e-brake. It wouldn't be the first time one got bent enough to make contact when the brake was released.

The e-brake light is a very simple setup. There is a switch on the e-brake pedal that when the brake is set it grounds the light circuit and the light is on. Much like the dome light operation. If that is fine then I'd look at the proportioning valve next. If it has air in it or a line is bent somewhere it can cause a condition where more pressure is in one circuit causing a piston inside to make contact with a switch on the calve again grounding the brake light and making it come on. To check the valve just remove the electrical connection see if the light goes out. If it does then the problem is in the actual brake system. If it does not then disconnect the light at the pedal see if it goes out. If not then start hunting down a pinched wire or broken insulation allowing the conductor to ground (short). If the light does go away when you disconnect it from the switch then get a new switch.

If your Truck came originally with a THM 400 then it should have a TV "box" somewhere close to the gas pedal. The THM 350 uses a mechanical connection for passing gear. It actually depresses a valve in the transmission sending the tranny into neutral opening up certain valves and it down shifts. The THM 400 is more electrical/mechanical but sort of operates similar. Its kind of a cross between the way the THM 350 passing gear works and the way a 200R4/700R4 TV works. The way the 400 does it is a better way then the THM 350. It is more pressure and throttle position orientated operation.

Just a thought.

I can get a th400 local that has a 73 date on it pulled from a chevy truck and has a deep tranny pan for $100.

Its got a newer torque converter and has a short tail. For that price is it worth picking up. Also I think they might use a different crossmember. My current one has just one bolt I think while the th400 needs 2(?).

I can't hear/see it run but the guy pulled it to go to a manual and says he would refund the money if I have problems. Any good way to check out a th400 that is not installed?