I finally got some info after hours of pouring over hydraulic fittings websites namely
http://www.discounthydraulichose.com/I've made a few discoveries.
All the hydraulic style fittings on German vehicles are of the type "
DIN" which stands for
Deutsche Industrial Norm .. This is roughly equivalent to the us
SAE FYI DIN has a 24 degree flare face
Another twist is that DIN fittings come in 2 grades - heavy and light.
These 2 grades are known by the industry as FDINLX (light) and FDINHX (heavy).
This grade impacts the thickness of the hole through the fitting, heavy being smaller ID because the fitting is beefier.
*You have to be sure that your hose size is the same between both ends when making a hose up from scratch.
Gates carries these fitting so your local parts store can probably get them but they charge a ton compared to the aforementioned website (almost 25 bucks / fitting at my local parts house).
A typical gates part for an 18mm female DIN to crimped hose
# is G25645 - 12 18
My problem was trying to find the appropriate adapters to go from my 22mm male DIN oil pan fitting to the k14 extension which is 18mm male DIN
I just ordered the reverse (female DIN) for each end for 3/8 hose and I'm on my way. I actually ordered a 90 degree bend and counterpart straight fitting to go in the middle too, but It's not required, I just want to ensure good fit. I plan to take the whole rig to my parts house once I fit and cut hose to length and have them crimp it for me.
FYI, the oil return coming from the k14 is about 3/8 so I don't anticipate any restriction.
Another wrinkle is the type of hose you use.. and it's heat / oil resistance rating.
I ordered a couple feet of Kevlar hose with stainless braid on the outside and a few feet of regular high pressure hydraulic hose..
I've seen people using things like heater hose for turbo returns so I'm thinking I'm safe either way, but oil coming out of the turbo is probably as hot as it gets anywhere in the engine, I'd guess in excess of 250 degrees f on a good day, maybe over 3-400f on a hard run.
Anyway, I hope this info helps someone save some time in the future..