One went flying, the other went by ship

These two letters were sent the same day Thursday 3 August 1950 by the same sender. The peculiar thing is that one was sent as an air mail letter and the other one as an ordinary international letter to the same address. The airmail letter has three  20 öre red Gustaf V, right profile. They are all perforated on three sides, one pair and one single stamp and hence came from a booklet, actually from the 64th booklet by Swedish Post first issued in 1942. It contained 20 stamps and the cost was 4 kr. Three 20 öre stamps makes 60 öre and that was the fee for   - 5 g air mail to North America in 1950. The other letter, which is a  - 20 g international letter, has two 15 öre brown Gustaf V, right profile. They are also perforated on three sides and they are from the 71st booklet first issued in 1945. A closer look at the 15 öre stamps tells me that these are of version I. For example the band of medals on the king's chest are less detailed and light. (This post deals with the two versions.)

Top: airmail letter to North America fee: 60 öre
7 March, 1942, 20 öre red Gustaf V, right profile. Qty: 98,000,0000 (pairs), 3-sided perforation
Bottom:  - 20 g international letter fee: 30 öre
14 February, 1945, 15 öre brown Gustaf V, right profile, version I. Qty: 18,400,000 (pairs both versions), 3-sided perforation

The letters were taken care of the Post Office Stockholm 1, the Post Office was co-located with the head quarters of the Swedish Post at 28 - 34 Vasa Street (Vasagatan 28 - 34), where the Swedish Post filled up two blocks.

On the the other side of the letter covers the following is printed "Josef Kastengren, Buhlsjö, Österbymo". It turns out that Mr. Kastengren got the first formal driver license in Sweden in January 1907. Well, people were driving along without a license in those days, but this guy was the first one to get a permit the right way. He was a driving instructor and taught the Swedish royals to drive as well, actually he taught the king on the stamps, he was also a car salesman and a business man in the Swedish car industry. Quite a legend.

Eventually both letter reach their destination. 1100 E. Hector Street, Conshohocken, PA.
(Google street)

43 years after he got his license he still seemed to be in the business because the letters were sent to the well known Lee Tire and Rubber Company in maybe less known Conshohocken, Pennsylvania. Famous for its car tires.The factory was built in 1910 by John Ellwood Lee, in 1965 it was bought by Goodyear and it closed down in 1980. But it did not end there. The old factory ground was turned into offices and called Lee Park and lately it has undergone some major renovations. It got a new name too, Spring Mill Corporate Center. In 1984 it was added to the U.S. National Register of Historic Places.

The odd thing is that the letter that not was sent as an air mail letter has "5 gr" written by hand, indicating that some one bother to put in on a scale. It seems like it was supposed to be sent by air too, the way that the stamps are applied and that they are from booklets indicates to me that it was most likely not done by Swedish Post.
. . . ah well, the mystery will remain unsolved.