I respectfully disagree with this post. That's a lot of work and unnecessary just to get them on the market. Don't take them apart. The fronts and backs are fine. Mask them off then scrub the cabinets with mineral spirits and 0000 steel wool and wipe them down. If you've ever used Pledge or a similar furniture polish with silicones, scrub them and wipe them down again. This shouldn't take you more than an hour or two. They appear to be in good shape, but your pics don't show much of the surfaces. Get yourself some Danish Oil. I'd get one can of Natural and one can of Regular Walnut and mix them 3 to 1. Flood the surfaces keeping them uniformly wet for 30-45 minutes. If there are some rough areas you can lightly wet sand them at this time with some 300 grit. Don't be too aggressive or you can burnish the surface- smooth is smooth, you aren't polishing the surface. You can apply with a rag, steel wool, paper towels, foam pad- whatever- just be mindful of the applicators between coats or when discarding. Submerge them in a jar of finish between coats or water if you are done with them. The curing process is exothermic. Fires have happened. Then wipe them down completely removing all the excess finish. You will do this process probably 3 or 4 additional times (allowing to dry in between)- or until they stop absorbing the oil (you'll be able to tell). ALLOW THE FINISH TO DRY COMPLETELY BETWEEN EACH COAT <- read that again! The amount of time it takes to dry completely will vary widely based on the climate. A warm, dry workshop- 24 hours or less. A cool dank garage- could be 3 days or longer. You can put a heat light or heather on them to speed the process. This may sound like a lot, but it's really easy even for a novice and does not require a clean shop. Most of your time is spent waiting. Shouldn't take you more than half an hour of easy wiping to apply each coat. Materials should be less than $50. Applying poly to any Heritage model lowers it's value imho. These aren't dining room tables. They do not need to be entombed in resin for durability. Oil finish is beautiful, easy to apply and easy to maintain- just give them a wipe on/off every 5 years or so with the Danish Oil.
Then fix the grills. I'd find a cheaper alternative to the Crites OEM black cloth. I did a pair of oak Cornwalls in an off-white grill cloth and I think they looked better than factory. They blended in the room much better. As always ymmv.