Well, at the time I purchased mine, several years ago now, I didn't find any reasonably priced TDI starters anywhere. Did they exist? Maybe, but nowhere I looked. I also spoke with the GoWesty folks at the time and specifically asked about the warranty, and they said they'd warranty the unit with a Tiico. Maybe they were blowing smoke, I don't know. And you'll note that I made no assertions about what's available *now*, simply gave a description of how mine has worked out. That *was* the question the OP posed.

Keith Hughes
'86 Westy GenV (Marvin)
 
 ------------------------------
 
 Date:    Wed, 25 Jan 2017 02:50:29 -0500
 From:    Karl Mullendore <tdiguru@WESTYVENTURES.COM>
 Subject: Re: Gowesty reduction starter user input please
 
 On Sat, 21 Jan 2017 22:43:09 +0000, Keith Hughes <keithahughes@YAHOO.COM>
 wrote:
 
 >I've been running their starter for 3+ years on an I-4
 (first with a Tiico,
 now an AVH 2L) without a problem. Easy install, low amp
 draw, and seems to
 work at anything above 11VDC. Pricey, yeah, but after
 several dead rebuilts
 in a near or so, seemed like a decent deal, and at the time,
 cheaper than an
 adapter and TDI starter (with no suitable core).  YMMV
 
 There are NEW TDI starters available of at the very least
 equal quality to
 the 'Gowesty' starter - for $75. Lactrical brand. No core.
 That gets you in
 for about $150 + shipping.
 
 And no, the IMI starter is not 'Gowesty's design'. It's been
 around longer
 than they have.