Static problems do occur on gas trucks,usually after the customer has switched from standard to white non-marking tires...the non marking tires don't ground the ruck to the floor and the operator usually gets a nasty shock getting on and off the truck...I had a customer that switched and I installed chains on all the trucks I used heavy 1/4 thick linked chain as it dosent wear as fast....I made them long enough so that there was 3-4 links laying flat on the floor underneath the truck....mounting point is up to you,wherever you have access to I guess

most static 'straps' are mounted underneath the truck off the frame, and generally they are only installed on electric trucks, if you have static problem on gas truck one has to be installed.
Their length is variable depending on where you mount it to, i have some for cat trucks and it is about 12 to 14 inches long.

if you want a chain you can mount it just about anywhere off of the frame as long as its out of the way from getting caught on anything and you custom cut the length depending on where your mounting it to.
If you dont see one hanging down then it got pulled off most likely