Service Parts Identification question.

[72timemachine]

If the spi sheet on the glove box door makes no mention of the rear end in your truck, would that indicate you do not have a limited slip rear end? This is the case on one of my '69 c30 parts trucks which has a ho72 rear end.

Conversely, my '72 C10 Cheyenne's spi has the posi-traction rear end listed. So the question is, if it is not listed as a posi-traction rear end on the spi, does that mean it's an open carrier rear end or would I have to jack up the rear end and do some further investigating?

Thank you for any help.