So that puts it well within 2000's so next check would be the Serial number on the back.
Usually is the 1st or 2nd digit (if multiple year) is the Ending Year.
Since it is a "Z" board, getting OEM parts may not be easy. The B/C even D version are recurrent.
Z refers to the assembly is being Amortized - meaning it's a last production run for that factory or point of origin. Parts being used up.
So as far a plate shield, the shield needs Grommets, tab holes even Zip ties. Nothing big, but you don't have the original template in which to even hand brake (bend) a shield. So you may need to use tin-snips, drill and files and even a grinder to make notches - or even a flat plate and use PC standoffs to mount the cover plate and leave the sides open.
That is - if you really want to.
IF the main board is shielded - then the shielding on the AMP board is moot, and can be troublesome for the metal will interact with the tuning of the amplifier. You may be sweating details that would be better off left alone and just work on fashioning a harness to fix your spaghetti wiring.
- examine the standoffs and mounting of that amp board. IF possible look for insulators - or spacers - because of reassembly - they may have missed a spacer and now you may have clearance issues for the parts to "breathe" and not contact the case or shield. (if you install one) or worse the spacers are on the wrong side of the board and it now hangs too low.
- "HI - Welcome to eBay - and the Well-Used Roller Coaster ride of undocumented changes and chances you take on playing with money to get other peoples' stuff they don't want"
If the amps been worked on, like pills replaced or such. Then putting a shield on it may not be the right direction to take.
What cause the pills to be replaced?
- - poor SWR or careless operator - you pick - both not good.
- - they may be "dumping it"
You have to understand that many amps in close proximity to the open circuit below - ground loops can form and if not addressed - will hurt the amp and even kill the radio from the board banded oscillation that can occur - putting a shield on an improperly neutralized amp (read this as no feedback resistors or changed values )changed for tuning of the amp to "peak out" at a frequency of interest - may invite more trouble than it's worth.
I would use a simple copper clad single-sided PC board (solid not perf-ed) and drill to match holes for the standoffs to hold a harness from getting too close to RF sections (power choke it) - and that means use a toroid - but mounting it away from the main PCB and within the amps shielding to contain the RF. So if this idea doesn't work, you can remove the PC board - you still have a board - an amp and a radio - but a slightly smaller copper clad board for projects of another type for later.