Transmission shifting problems

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I have a 72 3/4 ton pickup, the transmission was fine untill the drive blew the motor up (he never checked the oil) now the crank slaps against the block, like a sledge hammer, but ever since, the transmission, when you put it into drive, stays in first gear, take your foot off the gas, and it wants to shift up a gear but it really doesnt, like it is almost in second gear, but not quite, slipping i guess, what do you all think is the problem?

I have almost completed the rebuilding of the 350 chevy (2bolt) but i would like to trade the 4bolt "elcamino special" that came out of the truck for a transmission anyone near Austin? just dont want to put it all back together with that transmission and have spent the "wifes budget" on the truck already!