Overheat when placed in drive

[69RRJohn]

I've got a '69 girlymatic (on the floor) with 727 transmission. In idle, temperature gauge is where it's supposed to be. However, when I put it in drive, the needle nearly pegs. Appreciate any thoughts on what causes this and how it can be fixed?

 

[Russ69Runner]

How long has this been going on. John. Do you have a temp meter. Harbor freight sell's them. But I don't think the car is heating up it has to be a wiring problem. Is the car and original automatic car.

 

[69RRJohn]

Since I bought the car in February 2021. I don't have a temp meter and yes, all original numbers matching.

 

[V.R.D]

follow the temp wire from the sending unit back to the bulk head see if it has rubbed in to the wire harness

 

[69RRJohn]

Thanks..........will do. Appreciate all the help.