Mystery solved.
The early A1 (1965?) used the M151 brake lines during a transition period to the later configuration which is what was used on the A2.
So the A1 could have either depending on when it was built.
Thanks to everyone for their input.
M151A1 Front Brake Lines
Moderators: rickf, raymond, Mr. Recovery
Re: M151A1 Front Brake Lines
Here's a comparison of the lines. The A2 and late A1 lines are the two on the top, the straight 151 and early A1 lines are the bottom two.
You do not have the required permissions to view the files attached to this post.