Investing time (if you have it) might save quite a bit of money.
Not that it was asked...
Changing all of the door locks and ignition over may be in your best interest. I assume that eventually the Sprinter will be parked near where the keys were stolen.
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In the interest of general information.
As is fairly common for a vehicle the door locks use latches, not pins.
Note in this picture that the latches are held in place by using the key. Some suppliers keep the latches in place using a plastic sleeve.
Some web pages contain this:
ATTENTION!!
Don't pull out the key from lock before installation!
(That may unseat the latches. It can be difficult to return them to proper position.)
NAS aka NAFTA T1N?
IGNITION SWITCH + 4 DOOR LOCK BARREL SET FRONT LEFT RIGHT REAR MERCEDES SPRINTER
(Sprinter MK1 1995 - 2006) - includes ignition 10 latch cylinder
https://www.ebay.com/itm/IGNITION-S...108364?hash=item3ac2ba8b0c:g:BlMAAOSwE6VXJoot
https://www.ebay.com/itm/MERCEDES-B...h=item33b0cb410a:g:BSEAAOSw-0xYfNMY#vi-ilComp
BARREL LOCK DOOR SET KEYS FITS ALL DOORS MERCEDES SPRINTER C CLASS VITO VW LT (4 ea.)
https://www.ebay.com/itm/BARREL-LOC...887241?hash=item33c3894c89:g:PMAAAOSw8-FaV4wC
It is safe to assume that the ignition key has latches. Added: It 100% does. Note 10 latches in the picture above.
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NCV3
https://www.ebay.com/itm/MERCEDES-B...m=222011647324&_trksid=p2047675.c100005.m1851
Be aware that the title says older, but the "Fits" guide appears to list NCV3 models. The firm may also have T1N cylinders though.
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Future reference for others:
A reminder that this company advertises keys cut from cylinders.
Cut from lock cylinder.
They also advertise immobilizer service. Maybe not for MB immobilizers.
Staten Island, NY
https://paylesscarkeys.com/sprinter-key-cut-by-the-door-lock-cylinder.html
As Autostaretx Dick already mentioned. It would be worth verifying that a mechanical ignition key can be cut using a door lock cylinder [it can't. Door - 8, ignition = 10 latches], although that apparently doesn't apply for this thread with the stolen keys/different ignition.
vic
Added:
Having some lock experience, I'd be tempted to order the [correct T1N] 5 cylinders from the UK. The latches from the extra cylinder (4 ea. doors) might fit to re-key the existing ignition. By watching the video that I posted previously one can gain some insight as to how the ignition removal shouldn't be done.