help. cant find the culprit

[tim21391]

so i was goin on highway few days ago. and then i felt something different in the gas pedal.. then i look to pass somebody since i dont have a rear view mirror then i see im creating smoke so i pull off onto the shoulder and leave it running.. and i see oil coming out faster then u can pour it in.. i mean it was a constant flow.. and so i shut it off. and later that night got it home. and now today (sunday) i come to the the truck to try and fix it and i cant seem to find the leak i dont wann go spend $20 on oil just to see where its coming from since i leaked it all out.. i drove it up on the trailer so i think it still runs fine so i dont think i threw a rod or nothing.. what would you look for? when i seen it leaking it was right next to the tranny but it was motor oil.. but the lines were on the other side. the lines werent by where it was leaking.. any ideas?