Ron Guth: Two obverse hubs were used to produce 1934-D Quarter Dollars, as follows:
Medium Motto - aka Type of 1935 - IN GOD WE TRUST strong, but the letters are thin
Heavy Motto - aka Type of 1936 - IN GOD WE TRUST very strong, the top center of the W is higher than the left and right strokes (diagnostic)
No Light Motto 1934-D Quarter Dollars are known to exist.
Among the PCGS-certified examples, the most prevalent grade is MS-64. The finest example is a single PCGS MS67.
Sources and/or recommended reading:
The Washington Quarters of 1934" by David W. Lange, NUMISMATIST, September 2003, pp. 22-23