The dip stick tube on my 'K' Mustang looked a bit beat up so I decided to replace it. I bought two new ones several years back (I have more than one Mustang) and put them on the shelf. The replacement tubes would not fit. The diameter of the old tube is 0.371in, the diameter of both new tubes is 0.381in and the tube wall thickness is 0.025in. Stretching the tube end smaller or removing 0.005in of wall are not pratical. I pulled another 'not in pristine state' tube from a spare old engine that was assembled a month later than my 'K' engine and found it has a diameter of 0.371in. Not wanting to drill a larger hole in the timing cover, I used the one from the spare engine. I got the two new ones from National Parts Depot. Just a 'flag'.
Jim