Based on my observation of the boats going through the GB dealier in Bellingham, which we walk past every time we go to our boat, stainless rail stanchions began appearing in place of the original bronze stanchions in the early 1990s.
Stainless hand and grab rails began appearing as factory options in the later 90s.
For whatever reason, the cap rail on a GB has to be wood, so they will always have a teak cap rail even if there is no other external teak on the boat.
So far as I know and have observed, American Marine/Grand Banks has used the teak parquet flooring in all their so-called classic models, the original boats which today are continued only in the GB52. But the GB32, 36, 42, 46, 48, 49, and 52 all used the parquet flooring. I'm sure the factory would put in whatever an owner/dealer asked for and was willing to pay for, but parquet was the norm.
I don't know what is used in the new fast models, the GB41 "pod drive" boat, and the GB47. I've been on both, but can't remember what the floors looked like. The Eastbay uses, I think, teak and holly flooring. And I don't know what they use in their Aleutian models. Probably gold-plated marble.
GB began moving to stainless for a couple of reaons. One, good teak was getting harder and harder to get and so added a lot to the price of the boat. And more owners were wanting less external maintenance to do (or pay to have done.) However, external teak remained an option for anyone who wanted to pay for it.
We have one of the first GB36s made, and so it has a veritable rain forest of teak triim on it. One slip away from us is the very last GB36 ever made, and the only external teak on it is the cap rail and the transom.
Owners of older boats will sometimes replace teak hand and grab rails with stainless. A GB46 that we came close to buyng at one point is a good example. When we first saw the boat in 1998 or so, it had the full complement of teak hand, grab, and cap rails. A subsequent owner replaced the hand and grab rails with stainless rails. The cap rail remained teak because it had to.
Almost every GB model has a teak transom. Of course, on the fiberglass boats, the transom is fiberglass. But the hull mold has a rectangular recess in it in the transom, and the teak transom planks are set into that recess. They are bedded into the recess and held in place with screws. I don't believe they ever went to gluing the transom planks down because they are big and the transom curve puts a lot of strain on the boards.
I have seen one GB that was made with a flush fiberglass transom: no recess and no teak planks. So this was apparently an option at some point, or was perhaps a special order.
Most GB owners feel that external teak is part of the boat's character and so are reluctant to not have at least some of it; the transom for sure, the deck, and at least some of the longitudinal cabin trim that was used on all but the very last boats.
Some owners, when faced with a teak deck surface that's worn out prematurely from abuse or incorrect treatment, will decide to replace the teak surfacw with a fiberglass surface instead of paying to hae a new teak deck installed. We looked into replacing our boat's original teak deck with new teak in the early 2000s, and the cost at that time was about $30,000. Lord only knows what it is today.
If we had the time and the right tools and could afford the wood,we would love to take on the challenge of replacing our teak deck with new teak just to see if we could do it. But at this point, we don't have the time or the tools, and the cost of the new wood would be pretty staggering. So we take the best care we can of our boat's original deck.