350 Turbo Hydramatic to 700r4 Transmission in my 1978 K10

[Stodie78Chevy]

Okay so I have a 1978 K10 long bed with a small block 400 in it and a 350 Turbo Hydramatic Transmission. I am replacing my small block 400 with a new turn key 400. When info this replacement I also want to change out the 350 turbo tranny for a 700r4 with the overdrive. The new tranny Willy come with a new torque converter. Now my questions are what modifications will I need to make as far as the transmission swap? Will it oft right up? Do I need new crossmembers? What will fit up to the new 400 and what will I have to change as far as linkage and mounting and transmission cooling lines, ate they the same?

[bake74]

     You will have to locate the cross member and re-drill the mounting holes.  It should fit fine to your 400.
     Is your 700R4 going to be electronic or non-electronic ?  Here is a good article on wiring up a electronic 700R4.
     As far as all the lines go, someone else will have to chime in who probably has done the swap.

[Captkaos]

The 700R4 were never "electronic", but all of them had lockup converters and locked with a pressure switch.  You can actually but a manual toggle to lock it also.

Chris Lucas
73-87chevytrucks.com
captkaoscustoms.com
squarebody.biz

[pratherjoe]

Best way to run a 700R4 in a vehicle that didn't come out with one, is use a N/O pressure switch in the valvebody. Hook it into the 4th pressure tap, install this wire to the ground side of the TCC solenoid. Hook up a key on 12+ wire to the 4prong plug in on the side of the trans, use whichever pin goes to the hot wire on the TCC solenoid. The trans will act like a normal 350 turbo in the D position, but when you put it in O/D range the pressure switch will ground and lockup the converter. Makes it a lot cleaner shifting when driving around town.


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