I wonder how long these will last.

So long ago I got a dozen of these:
Antec ISK 300-150 and
http://www.newegg.com/Product/Produ...129080&cm_re=antec_isk-_-11-129-080-_-Product
Antec ISK 310-150
http://www.newegg.com/Product/Produ...129081&cm_re=antec_isk-_-11-129-081-_-Product

They came with what sounded like kinda sketchy PSUs, they are PFC, but the efficiency was terrible, 70%.

To my surprise these low-end design PSUs use mostly Nippon Chemi-Con and Rubycon capacitors, not a single one bulging after 4+ years of use.

But I'm wondering about the little buggers I can't get pictures of because it's soo tight in there, there's a couple green ones which have no brand markings.

Any idea who typically makes green caps with a polarity band that kinda looks like... Teapo?

It's really tight in there, less than half the height of a regular TFX.

I'm upgrading some of these ISK boxes, it'd be nice if the PSU lasted for many more years.

The clearances are scary, barely 1mm on the bottom and sides.

Those actually look like pretty decent PSUs, quality wise. Not great efficiency wise, but at 150w rating that really doesn't matter much.
Finding a direct replacement isn't going to happen.
If you're concerned about them you could switch to a PicoPSU, they should work fine.

As for how long those will last, it's really anybody's guess. Probably quite a while though.
The small misc. caps aren't under nearly the stress that the larger caps are, those do sound like Teapo caps, which are fine.
I wouldn't be terribly surprised if those PSUs lasted a decade (not another decade, mind you. That'd be asking a lot). I'd be more surprised if they died in the next couple years than if they lasted a decade, really.

If none of the caps are bulging I'd say you're probably just fine continuing to use them.

It's one of Antec's best/strangest products.

It's a very sturdy case, and it's Antec's second cheapest which comes with a PSU, has the best caps of any of their low-end PSUs, but is the least efficient PSU they make.

I guess heat will determine how long it lives, gets toasty under a heavy load, going from C2D/C2Q to i3/i5 is a big drop in power usage, even AMD APUs consume much less power idle.

Sanyo (now Sun) was usually green, and I have some green Nichicons