It looks like a sandman to me,M(Belmont)70 panel van 18v trim conferms it to be sandman.The skinny tag I think you may have doubled the 7 I think it should red 8M70RHJ592809Z,not 8m77.Of course the motor L32(253) being a capital L not l.I think 9/79 is a late HZ and a late sandman there will be others that will be interested in this tag information . The only other thing that would be good to know if the glove box door is original and has the right tyre placart and does the chassis number match the I'd tag numbers and therefore have the original chassis