C10 3spd colom shift convert to 4Spd floor 'box

[Paul C10]

I have a '74 C10 with the 3Spd Colom shift gearbox, I want to convert to a 4Spd floorshift 'box. (From South Africa) Do I have to do any modifications to the floor, is there a plate that needs to be removed etc ? I am new to the restoration business and only got the truck recently. It has the I6 250 motor which I want to keep, but I want to change to a 4 speed floorshift manual gearbox. Main reason the 3 speed box does bot have a low gear, for pulling etc. Please give some advise.
Thanks

[beastie_3]

The floor pan/transmission tunnel needs to be replaced with one from either a manual transmission truck or a 4x4.

http://forum.73-87chevytrucks.com/smforum/index.php?topic=11838.0

[zieg85]

How much highway driving do you do?  It may be easier to put a lower gear, numerically higher, in the differential unless you can find a donor truck with the 4 speed in it.  With the right hand drive it would be interesting to see the shifting linkage or is the transmission completely different from the left hand drives in the states?