Ok here's my reason why
1983 I bought a 67 factory BB/4 spd Formula S Barracuda (pic 1) put a 440 sixpac in it and ran it on the road for a couple of years. Then decided to make a race car out of it. So while I was in process of doing that I purchased a '79 D100 (Pic 2) for running. Put a smog 440 in it with a "509" purple shaft, Holley street dominator and a Holley 800 carb,and freshened it up, again just for street cursing. Wound up taking it to the track for something to do and it ran an 18 sec quarter spinning the whole way (well most of it) So I put a truck 8 3/4 in it with a sure grip and tried again still only moderate success down to 15 sec quarters, Then the big decision.... put a B body Dana 60 on top of the springs that I moved under the frame, cut the rear tubs to the frame and put a set of firestone 14X32 slicks on it down to high 12's. Pretty much hooked now on running a truck so I sold my "project " 67 Barracuda only to find and purchase my first Hemi (1988) so I put the mildly built hemi in the truck and dropped to low 11's. After a season of that I decided to put a tube chassis under that truck. wound up only improving to low 10's. The Hemi was too nice to keep beating on ( long story but it was basically a brand new '67 WO motor that had been sitting until I bought it in '88) so I built another one out of parts that had been a little more used. Proceeded to run in the 9's with this combo.
So that's one way some one starts racing a Truck
As additional info in 1988 the quickest truck in the nation was running 10.70. So that's one of the reasons I decided to build a tube chassis truck so I could be the fastest, but in the mean Time Koffels place built a B-1 motored Dodge truck that was campaigned in super comp and went deep into the 8sec range. (BTW...pretty fast ET's for the late 80's early 90's) So I came close but no cigar!
Now days every one has a truck!
And all my trucks are Plymouths! another long story

Pic 1