Hey Steg.
I think we are going to need some pictures to move forward on this one unless you are pretty sure you have a PE 1500. Send your pixs to
steve@vintaxe.com and I'll add them to your post for you.
Aria in the late 70's - early 80's used the PE prefix on virtually every solidbody electric they produced. It stood for "Professional Electric".
Most likely, your serial number indicates a 1978 model. During this time Aria used either a single digit year number like Yxxx or a double digit year number like YYxxx. Given you can eliminate 1984 as a possibility, the 8 probably stands for 1978.
I think with a picture we can probably figure out what model you have and then work out a value from there.