I couldnt find the answer I wanted in "search" but maybe I didnt look hard enough, so please redirect me if needs be
Had an RDLC too long ago with all the tools, strobe lamp etc, but have since sold or given them away
back to present times and I am a little ahead of myself but I would like recommendations for a 'budget' dial indicator to be used in the spark plug hole
of a DT 125 air cooled.  I see I could get a digital indicator and fab up a holder from an old spark plug but before messing around I would like to get some input
from all of you who have already been there.  
Just wanted to scope out where I am wanting to go throughout the year, hopefully.

Just wondering what year yours is & i guess yours has a center plug head.
[in my opinion] i can't see how it can be accurate with an angled plug like earlier models.
I think angled plug stayed on electric start models using the older motor design up past "74.
But the kick start model with the total motor rev-amp in "74 might've gone central from "74 on.
Happy to be corrected.

It could be a '78 with 6v, I looked in the manual and the dial indicator is screwed into the plug hole, even though the cylinder is angled forward

Angled cylinder doesn't matter. By "78 they'd all be center plug head.
Must be monoshock by that year.
Sorry though we were talking "75
Did you put a link up i can't get into.
Maybe not on this page. Might've been someone else.
Now i've found a pic of a "78 it reminds me i still have a monoshock from one wrecked a while back. Same color.
www.motorcyclespecs.co.za/model/yamaha/yamaha_dt125%2078.htm

@RT that's the beast, but as I said I am way ahead of myself as I am still in the negotiating phase with previous owner - I currently have no mount - very sad (however I see so many posts about timing so I wanted to get prepared and as friends offer me their tools etc. see what I actually need to do the job right)

i.imgur.com/ZZOdD5u.jpeg
 Here’s my 50 + yr old dial indicator 

I went with this option off EBay. Not the quality of the one that Ht1kid showed us, but it gets the job done.
imgur.com/a/2lOeoWk

OK so both of your indicators come with the spark plug adaptor and an extension, do you know what is a good length for the indicator to give a good reading once installed in the plug. Yes if I can get a Yam one I guess I will, but I may wimp out and look for a 'poorer' option and try to adapt it (maybe a bad idea given the accuracy of the measurement - 1.8mm)