Stock fuel sending unit with return line?

[ddp]

I'm doing a TBI engine swap into my 71 C10 and will need to add a return line to the stock tank. I don't have access to any of my factory manuals right now, but I see that the LMC catalog lists a return line in addition to the fuel and EEC vapor lines. They also list about 4 different sending units, including different units for 72 auto and manual transmissions.

Right now I have the single fuel and EEC vapor lines with a single line sending unit. The vapor line attaches to the top passenger side corner of the tank. I'd rather not modify my original tank and sending unit and would like to find a two line sending unit for the stock tank. I've seen a picture of one in a C20 in a TBI conversion thread.

Does anyone know what specific year, model, and application came with a stock return line and two line sending unit.

Thanks.