Transmission Tunnel Modification?

[Tod59]

Hey Guys-

I have a 59 short fleetside with a 6cyl and a 3 speed on the column. Plans are to install a 350ci and either an automatic 700r4 or 350 turbo transmission with the gear selector on a new Ididit steering column.

Question:
will my new size transmission require me to modify the floor or current transmission tunnel? My floor is pretty flat now, so I didn't know if there would be room or not for the new tranny.

Thanks
Tod

[_Ogre]

if you use the factory location for the 350 and go with a th350 there should be no sheet metal mods needed
if you go with the 700r4 the trans pan cover will not bolt on without a minor mod
but no real trans tunnel mods needed for any automatic, my floor is as flat as the day it was built in the factory

[OrrieG]

My 350/350TH with NP203 transfer case did not require any mods except for cutting holes in cover for the tranfer case shifter. Trans pan is a tight fit if you keep the factory crossmember between the rear spring shackle points and you will need to make a two piece torque converter cover. Some people remove the cross member entirely (not my recommendation because there is nothing to prevent the frame from spreading when loaded out of plane) or modify it so it can be removed and reinstalled.

[Tod59]

Thanks Guys!

[BigFrz]

looking to install a 6.0l in my 51 gmc. I need to know the measurements to tunnel the trans and pics of it if possible.
Thanks
BigFrz

[mr48chev]

If you run the crankshaft centerline in the same spot as the original engine you shouldn't have to do much if any mods to the floor above the trans in an AD.

If you raise the engine up higher in the chassis all bets are off as you will have to build a tunnel to fit. Some guys don't like the "way down there in the hole" look of a V8 setting with the crank at the same level in the frame as the six had because it tends to look lost down there rather than be up where it is visible from 20 ft away. Those are the trucks that usually end up with a big tunnel for the Trans.

My 48 has had the stock 3 speed a late 50's 3 speed, Muncie M21, Turbo 400 and a full syncro saginaw 3 speed in it over the years with only a slight rework of the lip at the front of the opening for the trans cover to clear the 400 as I was running it with a Camaro clip in the front.