I don't remember if I got the info about the replacement cable from this forum or the HIPO forum but here's what it takes to replace the cable on 65-68 Mustang heater blowers. The wires were showing thru the insulation on mine, so replacement was a good idea.
Take apart the motor. I leave this step up to you.
Carefully remove the field coil from the housing. The armature (the rotating part) can be left or removed, your choice.
Pic 1 - The end markings, note yellow ink. This motor is from a 66 San Jose Mustang with a build date in mid Oct 1965. On a 65 GT San Jose built in late June, the part number stamp on the motor end was in an arch with a 3/4 inch radius but in white. The date codes were the same color as the part number. I guess the part number is 16 point type, the date code is 14 point. They were stamped sloppy.
Pic 2 - The replacement cable from Virginia Classic Mustang (you're welcome Brant, besides I needed the ID tag to focus on.)
Pic 3 - This is what the insulation material looks like after 47 years of in a car. It appears to be paper, most likely with an adhesive backing. Note the "teeth" markings where it was cut off the roll.
Pic 4 - The original connection from the input cable to the armature winding wire was made with a crimp. I used my Dremel tool to cut the crimp off as I wanted the extra length (3/8 inch). It's a bit tight in there.
Pic 5 - (This is a secret method. Don't tell anyone.) I removed the insulation from a blue spade tip lug and then soldered the two wires together. The spade end is convienent to hang on to. The hemostat is a part of my tool box.
Pic 6 - Cut the spade off and trim the end. A ring lug will work just as well.
Pic 7 - Shrink tubing on the brown wire. (Hey, two stage paint and powder coating are accepted now, so shrink tubing has to be OK.)
Pic 8 - Do the steps in pic 4 thru 7 to the yellow wire. DO ONE WIRE AT A TIME, otherwise the motor may rotate backwards if you screw up.
Tomorrow I will bead blast the housing, paint the two ends and reassemble the motor. At that time I'll see if a piece of tape is required to further insulate the two connections internally. New stamps are being considered.
Jim
Addendum:
Instead of bead blasting and risking glass dust getting in the bushings, I used a wire wheel to remove the paint. What I found under the paint was a type of plating that used tin and lead, aka solder. It was an inexpensive surface finish used back in the 60's, soft but effective. I specified that type of finish on metal cans that were soldered shut after the electronics was inserted. I rejected the use of a chemical paint remover as cleaning up its residue might also damage the bushings.
I still have to get to the stamp makers to get stamps made.
Addendum - part 2:
Pic 11 - Here is an example of a semi-circular part number marking. The part number and date code are stamped in white. The date is Dec 2 1965 which makes it a mid 66 build. I do not know what plant installed this motor in a Mustang. Note the "toothed washer like grip" on the shaft.