904 Backup light Question

No they are not interchangeable. 1 wire switch uses the pic in the middle with no plastic on the comb. 3 wire switch uses the comb with the plastic on it. The switches themselves will screw into the case. If u use the 3 wire where the single wire was your back up lights will be on in drive. Kim. In the above pic number 1 is for up to 65. Middle is 66/67/68. 3 rd is 69 up.