It doesn't matter what year the bellhousing came from or what engine you are using, that is not the correct release arm
for a 58 truck. (Or any TF truck)
It needs to have the correct offset arm as I indicated previously. All TF trucks regardless of engine size (v8 or 6) or which manual
transmission it has, all used the same fork.
That one is for the later trucks.
Fred


1956 3100 Pickup/Red/350/3sp OD/PS/Disc Brakes
1957 Bel Air Sport Coupe/Red/355/TH350/PS/Disc Brakes
2017 Silverado LT Single Cab SB/Black/5.3/6 Speed Trans
1947 Willys CJ2A w/F-Head engine