W29 would have been the operational designation of the TX-29, which was development of the Mk-15 and was proposed for the Javajo, Redstone, and Snark missiles. The TX-29 was terminated in mid-1955 in favor of the W-39 development of the TX-15-X3.
Design
As this warhead was never tested its yield is unknown. However it is known that the warhead would have been 52 or 35 wide by 145 inches long and would have weighed in at 3,500 pounds.
References
W29 (nuclear warhead) Wikipedia(Text) CC BY-SA