1880 US Census (LDS)Household in Emporia, Lyon, Kansas
John D. Gunn, head of household, b:<1840> Canada, age 40, Train Master, billious, married, fb:Nova Scotia, mb:Canada.
Liela C. Gunn, wife, b:<1848> KY, age 32, keeps house, married, fb:KY, mb:VA.
Glenn D. Gunn, son, b:<1875> KS, age 5, (no occupation), fb:Canada, mb: KY.
Bessie Hamilton, aunt, b:<1809>, , age 71, b:Nova Scotia, fb/mb:Scotland
Rosalie Collins, sister-in-law, b:<1852> TN, age 28, single, (no occupation), fb:KY, mb:VA.
Lula Furman, niece, b:<1869> KY, age 11, (no occupation), fb:GA, mb:TN. [Lucy Furman]
Rosalie Furman, niece, b:<1875> KY, age 5, (no occupation), fb:GA, mb:TN.
Bessie Hamilton, aunt, b:<1809> Nova Scotia, age 71, (no occupation), widowed, fb:Scot, mb:Scot.
[Note misspellings Liela=Leila, Lula=Lucy.]

Evansville, Indiana Directories, 1888-92 Record (ancestry.com):
John D. Gunn, 402 Grant, Assistant Superintendent, 1888, Evansville, IN
John D. Gunn, 402 Grant, Railroader, 1889, Evansville, IN
John D. Gunn, 113 Line, Train Master, 1890, Evansville, IN
John D. Gunn, 113 Line, Clerk, 1891, Evansville, IN

http://homepages.rootsweb.com/~dobson/ky/kykenton.htm:
1888 "KY, a History of the State" 7th Edition (Volume), by Perrin, Battle & Kniffin (FHL book 976.9 D3wt; and from Evelyn Sigler 7/1982)
Lists J.D. Gunn of Toronto, Canada West. (see entry for father-in-law J.D. Collins).

John Donald Gunn's sister-in-law Rosalie Collins had a correspondence with a young artist named Maurice Gordon Gunn, who sent watercolored postcards to "Aunt Dossie (Rosalie's nickname). He was a later child of John Donald Gunn and Leila Collins; on a multi-state trek with their father John Dillard Collins, a surgeon, during the Civil War, Leila and her two sisters were taught as teenagers by a Maurice Kirby, whom they loved. Leila named a child after him.

Large Gunn family site is at OFTdb=cgm Cheryl Maxwell does not apparently list this Gunn.

Link between John Dillard Collins (1815) and Glen Dillard Gunn (1874). Letter from Nell Downing Norton to Glenn Dillard Gunn of 23 Jan 1942 states that JDC was GDG's grandfather. I recall as a child hearing talk of a 'Rosalie Gunn'.

Possible birth information about John Donald Gunn and a brother from NFGenWeb Vital Statistics Records
Newfoundland - Avalon South Region - St. John's District
St. John's - Parish of St. Thomas Anglican Church
Baptisms 1840 - 1875
PANL: Volume 29: Part 1 (http://www.genweb.ca/nfdata/045/vital/45_4vol29angbap1.htm)
John Donald Gunn, parents Donald and Patty, b: 19 Nov 1838, St. Johns, Bapt 25 Dec 1842, father's occupation servant.
Donald William Gunn, parents Donald and Patty, b: Nov 1836, St. Johns, Bapt 25 Dec 1842, father's occupation servant.

Not listed in 1900 census entry of wife and two children (see notes for wife), but wife is listed as married and not widowed.

• Married: 18 Dec 1873

1. Glenn Dillard GUNN b: 2 Oct 1874 in Topeka, KS
2. Maurice Gordon GUNN b: March 1885 in Kentucky
3. Allan Poindexter GUNN b: Nov 1886 in Kentucky
4. Donald GUNN b: abt 1882