How about a link?
According to Rock Auto, factory is 1/8" pipe
According to NAPA, they show a "low" and "high" quality, both 1/8" pipe
According to O'Reallys they show UNIVERSAL, one of which is clearly a WARNING LIGHT SWITCH. Their listing hardly inspires confidence in their catalog application listings.
For the record, I sold auto and truck parts, log chain and chokers, hydraulic hoses and fittings and industrial belts, chain, sprockets and related hardware for 15 years. I JUST DON'T REMEMBER ever asking a customer "do ya know what size" your temp sender is on a factory stock application.