Cletus , i'm sure you are aware but i will say it just in case . If you cut the 24 inches out of the gooseneck , it will not only lower it but also move back as the uprights are not vertical . I would guess the king pin will move rearward around 12" or more . This will cause the rear of the truck chassis and possibly the rear drive tyres to foul the gooseneck . You may need to use a 3/4" skid plate with forward gussetes to make proud of the front face to counteract the rearward movement of the pin . In short , i think the pin centerline will need to be where the old oscilator mount is now .