Most of the people here reporting are correct. Your truck is NOT rare. Bear in mind that this truck had a 14 year run. 1988 to 2002(Granted these were only 2500 and 3500 trucks). The 4 speed transmission was an "economy" transmission. Now while possible it may have been equipped with it from the factory, the odds are greater that its not the original. The floor is the dead giveaway with this. Cheaper truck...rubber mats and 4 speed trans. More expensive truck...carpet and 5 speed trans.
Now you want to go on about the front head lights and grille. Attached is a pic of my 1988. Now...the headlights were ORIGINALLY the single sealed beam bulb. These lights in my opinion suck noodles. So, the 4 sealed beam bulbs WERE options only on the 1988 and 1989 trucks. This is why you dont see many of them. 2 model years makes them a hard to find option. The grille....means beans. ANYONE who has ever taken off that plastic grille knows 2 things. One....they are extremely easy to remove. Two....they are extremely easy to break when that lower valance on the bottom of the grille decides to hang up on the bumper. So...If you notice...the grille on my truck is the same as yours. GMC grille on a Chevrolet. If you are not the original owner, everything you think you know....means nothing. If the glove box still has the RPO sticker, you can better prove your case on what options you have.
This truck I have...I have owned since 2002. I bought it cheap with a blown #7 piston. Originally, the truck was a 305 cu. in. with a TH400 behind it on a 10 bolt rear end with 3.08 gears. Why this configuration....I dont know. Originally, it had the rubber matting floor with no AC(had a Northern cold weather package meaning no AC and smaller radiator). I replaced the engine with a 350. After I moved to the Southwest, cash for clunkers brought in a plethora of these vehicles. So I took a rear slider window, a class 4 hitch, gave my truck AC. This made me completely re do the entire interior of my truck. New carpet, seats, dash, door panels and head liner. I also decided to give my truck OD. So I got a 700R4 trans. I was thinking of giving the truck a LS rear diff, but these trucks didnt have 5 lug rear ends with 3.73 or higher rear ends.
Now, the truck is getting another major surgery. It is going SAS. Ford Dana 50 front, Sterling 10.5 rear with a NV4500 GM manual trans and a Borg Warner 44-70 transfer case. The interior will be changed again to 2 bucket seats and a custom fiberglass center console. In 20 years when I am dead and gone, if this truck doesnt end up in a junkyard, some kid will think what the driveline is, will actually be what the truck came with. When in fact, it wont be. Your truck is 31 years old. Unless you are the original owner, you are merely speculating at this point at what is what.
How rare are the GMT400 trucks? Not rare at all. If you are gonna play the 2 out of X amount of so many made during a certain year....sure...you could deem it "rare". But in all actuality, its not. Since I am unable to find any production numbers....common sense should give you this....Lets say at minimum, 100K trucks a year....14 years.....1.4 MILLION on the road. This mentality is like the old school VW bug owners. They think they are incredibly rare and worth more than they are worth. In the end....20 MILLION were made and the vehicle is just a massed produced heap. Dont get me wrong....I love my GMT400. I even had 2. One was stolen in Vegas. But I understand that at the end of the day.....its a massed produced heap. Parts are everywhere. They are cheap and anyone can fix these things back to running order in no time. This tells you that the vehicle is NOT rare at all.
If you want a rare GMT400....the 454SS trucks would be the rare version. The SS 454 pickup was the performance truck produced by Chevrolet from 1990 through 1993. This truck inspired the birth of the Ford Lightning in 1993. The SS 454 was a rather rare truck, as only 16,953 were produced in three years. This was copied and pasted from Google asking how many 454SS trucks were made.
I apologize if I seemed harsh. This is not my intention. I merely wish to post factual information. Facts dont really care what your feelings or emotions are. Facts are facts.