Glad to hear you got the strap to fit. Looked through all the Chassis parts lists and the Chassis parts price lists which covered the 1935 without finding a listing for the long strap. But just because they were not listed does not mean they were not available through Service. Rather, they must not have been a popular item, and had to be ordered special. But maybe one bracket fit both 6.00 and 6.50 size tires. Today's tires probably have different dimensions than those in the 30's.
The 36-37 Pickup lists their long strap, 67-18307-B, as fitting both 6.00 and 6.50, and is shown in the 1936 Chassis parts list.
By the way, I am curious about what the 50-1395-A Spare Tire Cover and the 50-18305-A Spare Wheel/Tire Lock looks like. Any ideas?
Could this be the rascal that looks like a normal 35 locking cap but the strap is not pointing down - it is angled so it is useless on a passenger car . I see that part number is listed as 35 only in my orange bible so it is for spoked wheels . In a June 1935 parts book it is listed as model 50 only , 1935 only and hurd . I'm not into 35's but I have bought crappy 35 locking caps for parts and have had a couple like that . In the DeAngelis book on page 165 there is a pic of a pickup with a 35 looking cap and no cover or strap . On page 167 there is a pic of a panel delivery with what looks like a standard 35 tire cover and cap 
. No ******** it either but you can see that the strap out the bottom type wouldn't work very well . Like I stated earlier the oddball cap looks like a standard 35 locker but the strap cutout is at an angle