Under the hood, driver's side, on the firewall.
The bezel is widely known as a pie plate. There's no aftermarket source. That grille is popularly known as the "rhino chaser" or "rhino" grille, and it's not original to your truck. Check eBay - probably expensive.
- click on the images for more details.
Also, how do you know it's a '74? There was no wide track Cherokee in 1974. Post your VIN.
1) '77 J10 LWB, 258/T15/D20/3.54 bone stock, low options (delete radio), PS, hubcaps. 2) '82 J20 360/T18/NP208/3.73, KOs, 7600 GVWR 3) '75 CJ-6, 304/T15, PS, BFG KM2s, soft top 4) '95 VW Golf Sport 2000cc 2D