700R4, Is it necessary to lockup the Torq Conv?

[ck5566]

Will the trans work just fine in my 68 C10 w/o any lockup TC kit? Or is it **NECESSARY** to have some kind of TC lockup kit? And if one is used how much of a difference will it really make/ MPG /cooler/longer life? The truck WONT be used for Construction uses/heavy loads or long trips (2-5 hrs) steady driving on the highways (may be once in a while), just for every day "O" I need a truck for this or that you know those necessary times a truck is needed. thanks in advance