My '72 F100 is my first manual (3 on a Tree) truck and I'm having a bit of trouble when I shift into first from a full stop. I'll clutch, shift first, throttle slightly once the clutch starts to bite, and the truck will move under power but will jerk around a bit and spin the tires on the concrete. Anyone got a different way of shifting so this doesn't happen?

 

Depending on the gearing, starting out in 2nd works a whole lot better. Maybe "they" say you're not supposed to, but have been doing it for a long time.

 

My '68 F250 with the 360 has a three-on-the-tree, as did an old F100 with the 300 CI 6 cyl.
The thing I have always liked best about the 3-speed is its drive-ability. Meaning, since there are only three gears to get you from a dead stop to highway speeds, first gear is taller to begin with (2.99 in my '68) than it would be with a 4-speed (T-19--4.02), getting you from stop to somewhere beyond the point that you would have shifted into second gear with a 4-speed tranny ( T-18---2.41). I find that more desirable in traffic.
My '68 has been "awaiting revival" for several years, but I don't ever remember starting in second gear;(1.75) this would be the rough equivalent of starting a 4-speed in 3rd gear(1.41).
That being said, I think you may be having clutch problems.

 

The clutch "jerking around a bit" or clutch chatter is an indication of a worn out clutch. When/if you replace it all, have the flywheel resurfaced as it is probably dirty and grumpy.

 

Yeah I've tried starting in second but IIRC it has the same issue, thinking I might have some clutch issue. Might slap on a C6 autotrans if I can't work it out

 

Ford type 3.03 3 speed manual is an all synchromesh transmission. So when you shift, there is no grinding, including shifting down from 2nd to 1st.

However if the trans does grind, the 1st gear and/or 2nd/3rd gear brass syncro blocker rings are worn. If the clutch chatters, it's time for a replacement.

Pic: 7107 are the brass syncro blocker rings. There are two for 2nd/3rd, one (it's different) for 1st.

 

Thanks for the info! I think I found out what was wrong. Went for another drive and tried holding the clutch longer and it is completely smooth now. Thanks!

 

Yeah, hold it longer and give it a little more gas as your letting off the clutch pedal and it should be a smooth shift. There's a learning curve but you'll get the hang of it. You can start off in second like Tedster mentioned but you'll have it give it more gas when you disengage the clutch to keep it from lugging.