The L-4-134 and F-4-134 four cylinder engines used at least twelve different OEM distributors manufactured by Auto-Lite, Prestolite and Delco-Remy. There are at least a half dozen more knock-off versions from India, China and who knows where else.
The one thing that they all have in common is the distributor drive shaft. These distributors are driven by the engine oil pump by a key at the lower end of the distributor drive shaft. This shaft is identical on every 4-134 engine distributor. Therefore a distributor from a 1942 Willys MB can be installed in a 1968 CJ-5 and the waterproof distributor from an M38A1 can be installed in a 1946 Jeepster and so on.
So, in order to determine the correct service parts for your distributor you must first identify the distributor. All of the OEM distributors had an identification tag installed on them. Some tags were riveted and some were glued to the side of the distributor base. Others had a tag attached to one of the distributor cap hold-down clip screws on the side of the distributor base.
All Auto-Lite and Prestolite distributors had a tag on the side of the distributor base and have the distributor type cast into the bottom of the distributor base. These will be three letters to include: IAD, IAT, IAU, IAY and IGW. Delco-Remy distributors had a tag attached to the cap hold-down screw but did not have any casting numbers on the distributor base.
The aftermarket knock-off distributors usually have nothing attached or cast into the base to help identify them.
The simple method to determine the distributor model is to look at the top of the distributor body. Measure the outside diameter of the top of the distributor body and the width of the distributor cap locating slot cut into the top of the distributor body.
Go to our subgroup 15-04B DISTRIBUTOR CAPS and you will be able to identify the correct distributor cap by the measurements that you took from your distributor body. We list the distributor type with each distributor cap.