@sneaky_thunder the upgrade kit is extremely rare, i've found it around 2 times with pumped up spawn items on easy mode, but sewing kit is BEYOND rare, i have only found it once through my 20 easy mode playthroughs, and the 19th i was wondering if it even spawned in and i found it literally infront of me.
as others said, it can spawn anywhere, its just that the spawnrate of it is so low its incredibly rare, even for easy mode.
Upgrade kits though? they're usually found from military, if you have bosses that can spawn in then those guys are your best bet.

if you're looking for the secret furry items the IDs are as in the range of 34900-34920 as follows:
34900 - Pento's TAD Stealth Hoodie
34901 - James' TAD Stealth Hoodie
34902 - Pento's Titan Tactical Hoodie
34903 - Pento's Titan Tactical Pants
34904 - Peko's Tay Combat Top
34905 - Pento's Multicam Pants
34906 - James' Tay Combat Bottom
34907 - Pento's Tay Combat Vest
34908 - James' Tay Jumper Vest
34909 - Peko's Harley Heavy Rig
34910 - Pento's Bunny Ears
34911 - James' Fox Ears and Snout
34912 - Peko's Bunny Ears
34913 - James' Special WSC Round Mask
34914 - Pento's Protex Crew Helmet
34915 - Pento's "Tactical" Slouchy Beanie
34916 - James' Eddylite Extractlite Helmet
34917 - Peko's Tay Boonie Hat
34918 - Pento's Expedition Eagle II Backpack
34919 - Peko's Expedition Eagle II Backpack
34920 - James' 7.11 DASH24 Backpack
34921 - Pento's Bunny Tail
34922 - James' Fox Tail

This is all the ones i found i dont know if there are any more

You Can't find the multicam boonie or range caps, despite them spawning.

I can’t seem to find the crafting recipe for anything (upgrade or sewing kit as I don’t think you can straight craft the clothes). If anyone could let me know that would be fantastic! Thank you

Where can i find precision gear

Plz label the different Ids and the color item they spawn thx

How do I spawn them? I have been trying and it spawn nothing

I rly like this because its not so sleek so it fits in with the games design

neat clothing

W clothing mod