There is a Red plastic handled #5L in that catalog as a part of a set only.
I will look for it later today.

__________________
When in doubt, WHACK the GAS and DITCH the brake !!!

Yes, there is such a thing as NORMAL, if you have to ask what is "NORMAL" , you probably aren't !
Failure may not be an OPTION, but it is ALWAYS a POSSIBILITY.
ALL systems are GO for MAYHEM, CHAOS, and HAVOC !

The #5L handle is on page 21 of the 69-70 Xacto Catalog, only in the #92L and 95L Tool Sets. It does not appear as a separate item in the price list, so I assume it was only in the tool sets, unlike the #6L.
Just checked my three #5 knife handles; they all have the threads at the bottom of the collet and have the washer.
Did not check the #5 handles on my Hand-Drill and Coping Saw. They are on REALLY tight and I fear I would damage them trying to get them off the tools.

__________________
When in doubt, WHACK the GAS and DITCH the brake !!!

Yes, there is such a thing as NORMAL, if you have to ask what is "NORMAL" , you probably aren't !
Failure may not be an OPTION, but it is ALWAYS a POSSIBILITY.
ALL systems are GO for MAYHEM, CHAOS, and HAVOC !

Sue told me the customized & upgraded vintage set that she sold me was from the 1950's. My #5 handle looks the same as your first handle on the left ... threads on the bottom of the collet and a washer with the same width slot and she shipped to me with a NOS #25 blade chucked in it. That handle in your collection and most others I have seen appear to be a lighter red color and your is VERY clean as well.
The photo of mine is accurate mine appears to be almost a dark brown in color. Not sure if oils over the years made it turn darker or if it was always that color?

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__________________
Steve Naquin
TRA# 677 L2
NAR# 85518 L2
SAM# 0052

🚀 In Construction: Der Blue Maxx/Minie-Magg 5.5” & Vander-Burn MDRM Clone w/Stickershock23 Custom Decals
🚀 In Paint & Detail: USR Banshee
🚀 In Build Queue: Estes Doorknob w/Vander-Burn Rocketry Upgrade Kit [Sport Decor], Semroc Centurion-F, Semroc Egg Crate
🚀 In Repair: SLS Lil’ Hustler, SLS Aero-Dart 1969 Trim
🚀 Stay Tuned For Fall 2021 Launch Dates

My #5 handles are all the reddish dark brown like yours, Steve.

__________________
When in doubt, WHACK the GAS and DITCH the brake !!!

Yes, there is such a thing as NORMAL, if you have to ask what is "NORMAL" , you probably aren't !
Failure may not be an OPTION, but it is ALWAYS a POSSIBILITY.
ALL systems are GO for MAYHEM, CHAOS, and HAVOC !

The No. 3's showed up today; now I can X-Acto wherever I go.
(Have No. 3, will travel.)

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SAM #0031

A #7kp (knife pencil) that combines a #3 style knife collet at one end and a mechanical pencil at the other.
Only have seen them in catalogs, no idea when they stopped making them.

__________________
When in doubt, WHACK the GAS and DITCH the brake !!!

Yes, there is such a thing as NORMAL, if you have to ask what is "NORMAL" , you probably aren't !
Failure may not be an OPTION, but it is ALWAYS a POSSIBILITY.
ALL systems are GO for MAYHEM, CHAOS, and HAVOC !

I don't remember seeing them at Charrette ( the company I worked at where I bought most of my X-acto tools ) either and we carried the full line of X-acto. It is something I would have bought just because...
It is shown on the back of the card the No. 3 came on.

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SAM #0031

I like that No. 3 pen knife. I need to try to scoop one of those when one shows up on eBay again. I saw a seller a short while back in Italy was selling one I’ll need to check again over the weekend.

__________________
Steve Naquin
TRA# 677 L2
NAR# 85518 L2
SAM# 0052

🚀 In Construction: Der Blue Maxx/Minie-Magg 5.5” & Vander-Burn MDRM Clone w/Stickershock23 Custom Decals
🚀 In Paint & Detail: USR Banshee
🚀 In Build Queue: Estes Doorknob w/Vander-Burn Rocketry Upgrade Kit [Sport Decor], Semroc Centurion-F, Semroc Egg Crate
🚀 In Repair: SLS Lil’ Hustler, SLS Aero-Dart 1969 Trim
🚀 Stay Tuned For Fall 2021 Launch Dates

Good to know GH. I see many of the bright red #5 handles. Mine is in pretty good shape for as old as it is. No scratches or nicks on it I’m very happy with it I just wasn’t sure if it had faded to that dark color.

__________________
Steve Naquin
TRA# 677 L2
NAR# 85518 L2
SAM# 0052

🚀 In Construction: Der Blue Maxx/Minie-Magg 5.5” & Vander-Burn MDRM Clone w/Stickershock23 Custom Decals
🚀 In Paint & Detail: USR Banshee
🚀 In Build Queue: Estes Doorknob w/Vander-Burn Rocketry Upgrade Kit [Sport Decor], Semroc Centurion-F, Semroc Egg Crate
🚀 In Repair: SLS Lil’ Hustler, SLS Aero-Dart 1969 Trim
🚀 Stay Tuned For Fall 2021 Launch Dates

Estes Carried a full line of XACTO supplies as you know. Here’s some still in the packs offered in specials and sets. Also is a tiny pen knife from the 60s catalog, still in its wrapper, unused. Plus mine, which I got from Estes in the 60s,,built many thousands of rockets ! Note the old Glue Gun & Wind Meter !
Just For Fun.....

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ENGINE COSTS ARE " OUT OF SIGHT " .....