1988 Toyota 4runner - Spare Square Drive Shafts
You start by cutting off the tube from old shafts and 2 1/2" and 2" square tube with 1/4" wall.
You then grind the mating surfaces down to a square shape so they fit inside the square tube
I made this little chart to determine how long to cut each tube.
The rear shaft is 44" flange to flange
The front shaft is 32" flange to flange
Weld the tube to the ends
I used tube that had a welded seem so I ground a groove for the weld to slide into. Like a single spline drive shaft.
Slip them together to judge if they fit.