which sending unit? im lost

[sixtyeightchevykid]

hello, the other day i got in my truck and started it and noticed the gas gauge was pointing way past full, in about the 3 o'clock position, and so i did some research and troubleshooting and found that the gauge is fine the problem is the sending unit in the tank. so i went to my local parts stores and they cant get a sending unit, so i check lmc, and classic industries, they both have more than one sending unit listed. i looked at the one in my truck and it has a threded brass peice on the end where the line from the floor goes into it, and what i have found is that, that style is for a v8, i have a 250 inline 6 in my truck, so i need to know which to order? any info and input will be appriciated , thanks

http://www.classicindustries.com/tru...s/6428361.html
http://www.classicindustries.com/tru...s/6428362.html