Trans Swap?

[Del72Chevy]

I currently have a 72 Shortbed with 350 motor and 350 Turbo Trans 3 Speed Auto and 3.73 gears. I would like to put some sort or 4 speed automatic with overdrive. Anyone make this swap and can tell me what trans you bought. I am also planning on baggin the suspension so I was wondering if anyone knows of the clearance issues with the newer trans??

[PanelDeland]

Welcome to the BB.I haven't done the swap but some here have.Many use the 700R4 and really like it.Your rear gear will also play a part in the best choice.
Look thru the FAQ's section and you will find a thread on the 700R4 and maybe others.

[Bpokey]

You might look into a 200r4. They are the same length as a TH350 so you can re-use your driveshaft, I just had to move my crossmember back to the next set of holes in the frame, bend the lines a little, get some brackets to install the T.V. cable, run wiring to lockup the converter and I was on the road. I have 4.10 gears so having overdrive is great.

[swtman]

I just did this swap about 2 weeks ago. Still trying to get the bugs worked out but it's going to work great.Had to shorten the drive shaft about 3". Moved the cross member back about 2" I think. In my case I had to modify my shifter linkage but not really a big deal. Only trouble I'm working on right now is getting the torque converter wiring hooked up. Doing this on my own but I guess there are places you can buy the wiring harness and directions for hook up.I do love this setup though. Now I can drive 75mph at about 2300-2400 rpms. Much better then before. By the way my rearend gears are 3.73 if you're wondering. Good luck!

[Bpokey]

When I wired the lockup converter the only issue I had was the 4th gear lockup switch. On some the pressure from 4th causes the switch to ground the wire, on mine it opened in 4th. If this is the case you need a relay wired so when the switch un-grounds it will complete the circuit to allow the converter to lockup. If you have a junkyard close you can get plenty of relays cheap (sometimes free!). Just find one that is open when the ground and power are going to it and will close the circuit when the switch loses ground. I hope this helps someone, I was really puzzled when the converter locked up in all gears but 4th.

[JP2120]

Originally Posted by Bpokey

When I wired the lockup converter the only issue I had was the 4th gear lockup switch. On some the pressure from 4th causes the switch to ground the wire, on mine it opened in 4th. If this is the case you need a relay wired so when the switch un-grounds it will complete the circuit to allow the converter to lockup. If you have a junkyard close you can get plenty of relays cheap (sometimes free!). Just find one that is open when the ground and power are going to it and will close the circuit when the switch loses ground. I hope this helps someone, I was really puzzled when the converter locked up in all gears but 4th.

There are also 2 types of 4th gear switches. The normally open (NO) and the normally closed type (NC). You could get the normally open type and run your ground to it from the Lockup and then when it gets fluid it will complete the circuit. The above mentioned way would work great also. I just like to run as little wire as possible. Good Luck.
Duke

[Bpokey]

If you have the pan off that is the best way to go. I already had the pan off once and didn't want to pull it off again. Good info!