there was no "dash A/C" sold for a 3800 as an option.. you have to build one..
I installed dash air in my 1978 loadstar. I bought various pieces and put it together...
you could start with an A/C compressor bracket similar to this:
https://www.vanderhaags.com/detailvi...?part=24676340
that will mount you up a york 210 compressor.. sanden conversion is recommended..
https://www.fleetpride.com/parts/air...BoCMy0QAvD_BwE
then use an SD7 enhanced compressor. most likely a 4805 which is ear mount 8 groove fllat belt.. wil likely drive off the main serp belt.
https://sanden.com/enhanced-compressors/
condenser.. something like this works..
https://buspartexperts.com/products/...irt-60-000-btu
or a CS2 carrier / ACT(ACTi is defunct but parts may exists).. or a CM2 MCC...
evaporator... I used one like this (retro style 36,000 BTU) in my loadstar.
https://www.ebay.com/itm/11239595494...QFG2BXNA19G9NN
then you'll need line and fittings... setup like that you can get away with #10 suction line (evap to compressor), #8 discharge line (compressor to condenser) and #6 liquid line (condenser to evap)..
I use reduced diameter barrier hose..(goodyear 4890). hard to tell you how many feet of each you'll need as it depends on where you mount the skirt condenser...
I use bugaclip / burgaflex fittings which go together very similar to the older style clip-based PEX fittings.. you use a burgaclip crim tool (easy to use).. to crimp the lines..
with fittings I really didnt know what I needed till I got all my components and could then make a shopping list for hos and fittings..
coldhose is a great resource...
https://coldhose.com/collections/BurgaClip-female-oring
https://coldhose.com/collections/reduced-barrier-hose
wiring is custom... you'll want to relay control your condenser.. I use a high power relay because of the start current. I set mine up so the condenser relay is triggered any time the inside fan is on.. this way you dont have the condenser fans going on and off every time the compressor cycles...